Steve McQueen's 1963 TT Special
Joshua Trees, Mojave Desert, California [Photo: Charles Rising]
The Mojave Desert stretches predominantly across southeastern California and parts of Nevada, Arizona and Utah, encompassing approximately 25,000 miles of arid, often spectacular landscape, peppered with strange rock formations, animal life and vegetation, including the Joshua Tree, a variety of yucca plant unique to the region. Named after the Mohave Indian tribe, it is often referred to as “high desert” because it is largely 3,000 – 6,000 feet above sea level, though it includes areas which are both much higher (Charleston Peak at over 11,000 feet) and lower (Badwater in Death Valley, at 282 feet below sea level).
The desert has from time immemorial exerted a powerful pull on mystics, ascetics and others of a spiritual disposition as a place to go for contemplation, meditation and to seek enlightenment: Jesus Christ himself, for example, retreated in solitude to the wilderness on more than one occasion to quietly reflect on things, and do battle with the Devil. The wide-open spaces of the Mojave have similarly acted as a magnet to many seeking to escape from the demands of day-to-day life, to find inspiration and recharge their batteries, particularly among the artistic and musical community.
Country singing legend Gram Parsons would often take off to the Joshua Tree Inn when he wanted to get away from it all - generally loaded down with a bag of heavy pharmaceuticals and a groupie or two in tow - foolishly snuffing out his life on September 18th 1973 when, in room 8 of the inn, he thought it a good idea to inject himself with a heroin and cocaine ‘speedball’ (or liquid morphine, accounts vary). His wishes to be cremated and have his ashes scattered over the Joshua Tree Park were (partially) fulfilled by his entourage who managed, by nefarious means, to obtain his body in its casket and set it on fire in the desert. Authorities were alerted however and his charred remains returned to his family for a ‘proper’ burial (sadly, not what he wished for at all). Bono of U2 in the ‘80s was another who fell under the spell of the Mojave, naming the band’s fifth, best-selling album, ‘The Joshua Tree’ after it.
Others just enjoyed getting out into the isolation of the high desert to escape the crowds and reenergise. For many, this involved barrelling off into the distance on a high-powered motorcycle – “cow-trailing” in US parlance - as well as taking part in races. In an interview in the August 23, 1971 issue of “Sports Illustrated”, Steve McQueen described the allure of the desert, and his revelation, having ingested hallucinogenic peyote buttons, that trying to tame it was not only impossible but a ludicrous idea in itself:
“I first began to understand it as a living thing back in my wilder days… I was interested in the Indians and they had given me some peyote. This was way before the drug culture got started, and people were still serious about the philosophical aspect of the hallucinogens rather than just kicks. Anyway, the peyote really hit me. I took off into the desert on my bike, bound and determined to whip it. I ran flat out, straight into the desert – I was all ego, challenging every bump and every gulch. I don’t know how many endos I turned, plenty of them. The cactus ripped me up, the rocks chewed on my hide, I had sand in my nose and kangaroo rats in my ears. I rode until the bike ran out of gas, and after that I just lay there.
It was dead quiet, night falling and my bike making these little crackling noises as the metal cooled and settled. I knew then that that not only could I never whip the desert, but that the whole thought of trying to whip it was the most ridiculous idea in the world”.
Competitive as McQueen undoubtedly was, desert riding to him was never all about racing. “You end up pushing farther and farther into the boonies… trying to escape from other people and their noise and their crap, but then they see your tracks and they follow you. It’s the problem that confronts all of us in a jam-packed world. Who are we running away from? Answer: us. It’s crazy, but what’s the solution?” As well as racing, he simply enjoyed riding out with a small group of friends and having fun. By 1971, with the desert becoming increasingly closed to motorcyclists for ecological reasons, the future was looking bleak for those who enjoyed desert riding.
A decade or so previously, things were a little more relaxed. Desert racing and riding was a popular pastime for many Californians. For the 1963 season, Triumph finally conceded to requests of Johnson Motors, their West Coast distributor, and built two new models designed exclusively for US off-road use. The 650cc Trophy Special, a stripped down version of the single-carb Trophy which had long been a favoured basis for desert sleds, was specifically targeted towards desert riders and racers. But hotter still was the Bonneville TT Special, the twin-carb version, promising maximum horsepower and thrills. While most experienced desert racers preferred the greater reliability of the Trophy, there were those for whom nothing less than “the fastest production motorcycle in the world” would suffice. And that motorcycle was the Triumph Bonneville TT Special.
McQueen aboard a 1966 TT Special in the desert for the "Popular Science" review
Don't think those pipes would last long in the desert!
Steve McQueen was one who favoured the Bonneville (and particularly the TT Special) over the Trophy as for desert riding. In the November 1966 issue of "Popular Science" magazine - in which he is photographed on a 1966 TT Special - he said: "My feeling has been that the Triumph Bonneville 650-cc has been best for the desert until recently, when the lightweights started to nip at its tail. It has more wins in desert racing than any other bike." [I'm not sure about the accuracy of that statement, but still - strictly speaking, surely that accolade applied to the Trophy, not the Bonneville?]
1963 Johnson Motors T120C Bonneville TT Special DU1683, at auction in Las Vegas, January 2016
[Photos courtesy Bonhams]
On 30th October 1963 (according to the 1971 title) McQueen purchased, through his film company, Solar Productions, Triumph T120 DU1683 (above). Triumph factory record information held at the Vintage Motor Cycle Club in England – see below - for the machine identifies it as one of the all-new unit construction “West Coast T120C” Bonneville TT Specials.
Engine assembly record
Engine stamp: T120 DU1683
Engine build date: 2 Feb 1963
Comments: “ET Tachos 17t Sprockets”
Assembly Record
Lighting: Tacho [Lighting column was hardly ever completed and when it was it was usually just notes, such as this, unrelated to “Lighting” as such]
Order #: 6564
Build date: 4 Feb 1963
Build record comments: T120 [in 1963, just “T120” or “TR6” was recorded in the assembly record for model identifier]
Despatch record
Model: T120C
Order #: 6564
Despatched: 13 Feb 1963
Supplied To: JM USA
All 1963 T120s had engine stamp prefixes of “T120” – use of the differentiators of “T120C” (Competition) and “T120R” (Road) having been suspended for the 1963 model year, and only the “DU” number was stamped on the frame. The sole way therefore to identify the different US variants is by reference to the Triumph factory records. DU1683 has never before been identified as a TT Special, surviving examples of which from the 1963 model year being the rarest of them all.
Engine stamp for DU1683 - no 'C' or 'R' differentiator on 1963 US Bonnevilles
[Photo courtesy Bonhams]
DU1693 engine stamp, another West Coast T120C from the Feb 1963 batch - note consistency with the McQueen engine stamp
[Photo: Charles Rising]
In this case, the engine assembly record informs us that the machine had ET battery-less ignition and a 17 tooth gearbox sprocket – both common only to the Bonneville TT Special. The TT Special was also fitted with a tachometer (confirmed in engine and assembly records) but no speedometer. In 1963, it would have left the factory with E3613 12:1 compression ratio pistons – usually, but not always, stated in the engine record. The despatch record confirms DU1638 was despatched to “JM USA” (Johnson Motors) and was a “T120C”. It was thus one of the second batch of T120C TT Specials built for 1963, out of a total of 315, all but 50 being despatched to Johnson Motors.
Early on in its life (in all likelihood, from new), Steve McQueen commissioned his friend Bud Ekins, legendary racer, stuntman and bike builder, to convert what is in all probability TT Special DU1683 into a desert sled for recreational use in the high desert and racing. The specifications of the desert sled are described in an interview published in the June 1964 issue of “Cycle World”. One of the first things Bud did was to replace the 12:1 high compression pistons with standard road-going Bonneville ones of 8.5:1 for greater reliability, according to the review. JoMo Service Bulletin 5-63 warns specifically against using the E3613 pistons for desert racing: "The T120C is a Special Competition Model... It is fitted with 12 to 1 compression ratio pistons... this high compression ratio is not recommended for desert competition or prolonged highway use!" While some did use high-compression pistons for desert riding - such as the previous owners of my 1966 T120C TT Special and Rodda Thomas's 1967 T120TT, both of which were used as desert bikes but had their original 11:1 pistons fitted when re-imported from California - most riders swapped them for standard compression ones.
Rodda Thomas' 1967 T120TT in use in California as a desert bike, fitted with a Ceriani front end and high level pipes. Original 11:1 pistons were fitted when Rodda acquired the bike in similar guise to above. My 1966 TT desert bike also had original 11:1 pistons fitted. Generally, for desert competition however, where reliability was more important than performance, 8.5:1 or lower compression ratio was the norm for Bonnevilles and Trophies.
JoMo TT cams were fitted to give a little more top-end power. The “sagebrush-snagging oil pressure indicator was converted to a pop-off relief valve with a return line back to the oil tank”.
"Oil pressure indicator was converted to a pop-off relief valve with a return line back to the oil tank"
[Photo courtesy Bonhams]
According to “Cycle World”, the front wheel was replaced with a “1956 Triumph hub and 19” wheel to reduce unsprung weight” and forks were fitted with heavy duty “sidecar springs”. Rake was “increased slightly” by “altering the frame at the steering crown”. The “rear frame hoop was bent upwards to accommodate a 4.00 x 18 Dunlop sports knobbly and to it were welded brackets for the Bates cross-country seat”. Handlebars were “by Flanders, with leather hand guards” and throttle cables ran “over the tank through alloy brackets to the twin 1-1/8” Amal carburettors”.
1956 Triumph hub and 19" front wheel
[Top photo courtesy Bonhams, below detail from one by Cal West, "Cycle World", June 1964]
"Rear frame hoop was bent upwards... and to it were welded brackets for the Bates cross-country seat"
[Photo courtesy Bonhams]
Handlebars "by Flanders, with leather hand guards". The bars now fitted to DU1683 are neither Flanders nor standard T120 bars, but the leather hand guards are visible.
The reference to 1-1/8” carbs is interesting because the 1963 TT Special is usually described as having 1-3/16” carbs. However, the E5727 cylinder head with tapered manifolds designed to accommodate the bigger 1-3/16” carbs was not introduced on the TT Special until 1964, and I’ve always found it questionable whether the West Coast T120Cs left the factory with the bigger carbs in 1963. I feel it more likely they were fitted as an option by dealers using a JoMo supplied kit (which was available). The May 1963 issue of “Cycle World” is adamant that the TT Special they tested (which would have been from the first batch) was standard engine-wise, and this was recorded in the review as having the 1-3/16” big carbs. However, I have it on good authority that, despite claims to the contrary, the bike had been extensively tuned by JoMo, and a carb kit could have been fitted as part of this work – which would explain why it achieved a test speed of over 123 mph. I find it very hard to believe that a standard TT Special – which had the same engine as the T120R with higher compression pistons and (possibly) bigger carbs, would have achieved this speed.
"Oil tank was modified to increase capacity and bring the filler out the side..."
[Photo courtesy Bonhams]
“The oil tank was modified to increase capacity and bring the filler out the side from under the seat”, also serving “as part of the mudguard, saving weight”. Air filters consisted of “paper pack cleaners connected by a special collector box to the carbs”. “This box is finished in black wrinkle-finish paint while the tanks are dark green” [though they look black in a colour photo]. Long cross-over pipes designed by Bud Ekins and exiting on the left were fitted, “left unplated for better heat dissipation”. A Harlan Bast bashplate was fitted, "footpegs were braced and the rear brake rod was increased to 5/16" diameter and rerouted inside the frame and shock (where sagebrush can't damage it)".
Note the modified kickstart - this was necessary to provide clearance for the high level pipes - which would have been a later addition.
"Paper pack cleaners connected by a special collector box to the carbs"
[Photo courtesy Bonhams]
The photo above shows much of the detail described in the "Cycle World" article. Note the "special collector box", which looks like a modified variant of the original with a more effective air filter on one side.
Clearly shown too is the modification made by Bud to the rear brake operation. A pre-unit brake pedal has been fitted , operating the thicker 5/16" (1/4" as standard) brake rod through a slot cut into the engine plate. Note where forceful use of the brake has worn the centre engine bolt. The pedal stop has been made redundant and has been rotated out of the way beneath the pedal.
Note the metal scrambles-style footrest with plate behind to protect the primary cover - same as in the "Cycle World" photos of #502.
The tank badge mounting holes on the petrol tank are clearly visible - as they are in the photos of #502 and #141. It seems strange that these were never filled in, given the tank was never going to be fitted with badges, but still.
Steve McQueen on a 1963 Triumph Bonneville, race number 502, which originally had 12:1 pistons (unique to the T120C TT Special). Is this T120C DU1683? Probably...
[Photo Cal West, "Cycle World", June 1964]
Front and detail photos of the McQueen Bonneville desert sled
[Photo Cal West, "Cycle World", June 1964]
Drive side showing throttle cables routed over tank. Note checkpoint card taped to the top of the tank. In a desert race this would be signed by each person manning the various checkpoints en route and would provide evidence that the course had been completed.
Bud Ekins high-level pipes fitted to my 1966 T120C TT Special Mojave desert sled
A colour photo of McQueen with bike 502, looking much as it did in "Cycle World"
Note Steve is dressed the same in white T shirt, the Lewis Leathers 935 leather jeans he favoured, and Red Wings-style boots. It would seem likely the photo was shot at much the sam time, and the bike is still looking relatively new. Note tanks seem black - not "dark green", as claimed in the article.The Triumph logo looks hand painted, as opposed to a decal.
McQueen freeing the clutch on what looks very like a later incarnation of the bike featured in the June 1964 "Cycle World" review. This time it has race number 141.Was this the bike he "took off into the desert [on]... bound and determined to whip it"? Note in this photo one can make out the throttle cables running "over the tank through alloy brackets to the twin 1-1/8” Amal carburettors”. DU1683 as it appeared in the 2009 and 2016 Bonhams catalogue photos had cables routed more conventionally under the tank.
Wear on the tank shows white underneath - possibly the original Triumph white. Heat shields on exhausts, safety wired float bowl, no chrome shrouds on rear shocks as on #502.
Another shot of bike #141, this time looking like it's just been/or about to be raced. Wear on the petrol tank, checkpoint card visible on top. Note the different bash plate arrangement. The Harlan Bast one featured in the "Cycle World" review seems to have been replaced by a standard Triumph skid plate - as fitted to the T120C and TR6C as standard - and an engine case protector with perforated holes. There is no skid plate fitted to DU1683 in its most recent incarnation.
Advert for the 1963 Harlan Bast Triumph skid plate, as fitted to #502
No sidestand or lug on DU1683. Possibly removed to allow a Harlan Bast skid plate to be fitted? Lug and sidestand had been removed from my 1966 T120C at some stage, possibly for the same reason (or maybe the lug just snapped off, quite common!) Note the metal scrambles-style footrest with plate behind - same as in the "Cycle World" photos of #502.
Close up of engine case protector fitted to DU1683 - remarkably similar to that fitted to bike #141.
It’s very likely that the bike numbered 141 is the same as that featured in the June 1964 “Cycle World” with the #502 race plate, perhaps later in 1964 or in 1965.The similar modifications shared between bike 502, 141 and DU1683 makes it likely that the DU1683 in its current guise is the same as bike #141 - with modifications such as the Rickman-style pipes, higher bars and resprayed tanks.
"Built by Von Dutch at Bud Ekins motorcycle shop". Lot description for DU1683 when sold as part of the McQueen estate in 1984. [Photo courtesy Bonhams]
T120C DU1683 was originally sold as part of the McQueen collection at the Imperial Palace and Casino auction on November 24th/25th 1984. I have read that it was then stored in the Trev Deeley museum till 2007. It was then sold by Bonhams on 9th May 2009 at the Quail Motorcycle Gathering, Carmel, for $84,240 (£64,364). By this time (and quite likely when sold in 1984), the petrol tank had been repainted, in dark green but with no Triumph logos. The rear fender is shown as being shorter than on the earlier photos of #502 or #141.
In January 2016 DU1683 was auctioned for $103,500 (£79,079) including buyer’s premium in at the Bonhams Las Vegas auctions as part of the Larry Bowman collection. The 2016 lot description claims the paintwork was by Von Dutch – although I find this hard to believe. The lot description when the bike was originally sold as part of the McQueen estate in 1984 (see above) states that it was "Built by Von Dutch at Bud Ekins motorcycle shop". This could have been true - Kenneth Howard a.k.a. Von Dutch did in later life work with Bud on restoring motorcycles - but he was better known as a custom painter, particularly renowned for his pinstriping. The green paintwork on DU1683 as sold in January 2016 is not typical of Von Dutch's work (no Triumph logo or pinstriping) and I suspect the claim that it was his was due to a misinterpretation of the lot description at the 1985 Imperial Palace auction.
It's interesting that white paint is shown underneath the green petrol tank - as is revealed beneath the tanks of #502 and #141 - possibly the original white (for 1963 T120s) Triumph paint.
As sold in 2016, DU1683 looks similar in appearance to the Rickman Métisse Mk 3 scrambler with the same pipes and painted a similar green to that used for the majority of them. I have even read of it being referred to as a Métisse when it was in the Trev Deeley museum. The Mk 3 Scrambler was introduced in 1962, but with low level pipes. I understand that the high level ones as fitted to DU1683 were developed especially for the US desert racing market, around 1965. McQueen bought a Rickman frame kit in 1965 or '66 and built, with the assistance of the Ekin brothers "in our valley shop" his own desert racer, fitted with a 650cc Trophy engine and painted battleship grey. He said of it in "Popular Science", "The rig is the best handling bike I've ever owned. And the power - it's supersonic!"
Magura brake lever. A later addition, presumably. Though Magura, a German company, has been around since 1893, I don't believe they started supplying motorcycle accessories until the late '70s/'80s (TBC)
It's likely that the Rickman would have become McQueen's main desert bike, certainly for racing given its greater competitiveness to the 1963 TT Special. From 1965 or 1966 it's likely that DU1683 didn't see much action. The addition of a Magura brake lever (see above) looks to me like something that in all probability would not have been made until sometime after 1980, and therefore would not have had anything to do with Steve McQueen. I get the impression that this bike was used early in its life, then perhaps stored for a decade or more, and then crudely commissioned with new bars, brake lever, paintwork and pipes and put to further off-road use before being sold in 1984.
Buyer’s premium on the 2016 $103,500 sale would have been approx. $26,000 (though may have been reduced as it was a large collection being sold) so the vendor would probably have received a minimum of $77,500, thus losing a maximum of $6,740 (plus insurance and storage costs) over nearly 7 years. Maybe if it had been advertised as a 1963 West Coast T120C TT Special it would have fetched a bit more given the added rarity as well as the provenance, who knows? The 1963 T120C TT Specials are the rarest of all, with just 315 leaving the factory. Due to the absence of the 'C' or 'R' differentiators on the engine number prefix (relied on by many to identify the model), many of these have been restored as standard T120 roadsters, their owners unaware that they have a far rarer variant!
Summary
We have potentially 3 different Triumph T120-engined desert sleds here, all of which either were owned or used (or both) by Steve McQueen:
1. Triumph Bonneville desert sled with race number 502 featured in June 1964 "Cycle World". Also pictured in a colour photo, which seems to have been taken at much the same time as the "Cycle World" ones judging by appearance and attire of McQueen and condition of the motorcycle.
2. Triumph Bonneville desert sled with race number 141 featured in two monochrome photos. This bike shows considerably more wear and tear than 141, but appearance of McQueen suggests it is taken no more than 2 year later, and possibly much closer in time. Wear to bike suggests both photos were taken close together in time
3. Triumph Bonneville T120C DU1683 sold in January 2016, with evidence showing it was originally sold as part of the Steve McQueen estate in 1984, after the actor's death.
Specifications
1. Triumph Bonneville #502
8.5:1 pistons (fitted in place of original 12:1 pistons, unique among US T120s to the T120C TT Special)
1956 hub with smaller brake plate fitted with air-scoop
Harlan Bast skid plate
Special collector box with external paper air filter
Flanders handle bars
Leather hand guard on throttle side
Straight through high-level, unplated Bud Ekins pipes exiting on the left
Single, Triumph-type heat shield on one pipe
Modified oil tank with increased capacity and filler on the side (instead of top)
"Dark green" oil/petrol tank (according to "Cycle World", though they look black in the colour photograph)
"Triumph" logo in white, appears hand-painted
Bates seat
Rear frame hoop bent upwards
Headstock bent to increase rake
Bracket welded to rear frame to support seat
Braced scrambles-style foot pegs with plate behind
Rear brake rod increased in diameter to 5/16" and re-routed inside frame/shock (standard diameter 1/4" and routed outside frame/shock in '63)
Pre-unit brake pedal. operating via slot in engine plate
PRV with return line back to oil tank
Throttle cables running over tank through alloy brackets to carbs
1-1/8" Amal Monoblocs
Shocks with chrome shrouds, black lowers (reverse of std Triumph shocks)
2. Triumph Bonneville #141
1956 hub (as 502) - brake plate not visible in photos
Unidentified perforated engine case protector
Triumph skid plate
Special collector box with external paper air filter (as 502)
Flanders handle bars (as 502)
Leather hand guard on throttle side (as 502)
Straight through high-level, unplated Bud Ekins pipes exiting on the left (as 502)
Perforated after-market or custom-made heat shield over both pipes
Dark coloured petrol and oil tanks, possible black or green (as 502)
"Triumph" logo in white/light colour, appears hand-painted (as 502)
Bates-style seat similar to 502, though texture of cover looks smoother, "nose" is worn through and shape is different
Rear frame hoop bent upwards (as 502)
Bracket welded to rear frame to support seat (as 502)
Foot pegs not clearly visible in photos
Rear brake rod/pedal/modified engine plate not visible in photos
PRV not visible in photos
Throttle cables running over tank through alloy brackets to carbs (as 502)
Black shocks, no shrouds (possibly as 502 with shrouds removed)
9 matching modifications with #502
3. Triumph Bonneville T120C DU1683
1956 hub (as 502 and 141)
Brake plate with air scoop (as 502)
Unidentified perforated engine protector (as 141)
No skid plate
Special collector box with external paper air filter (as 502)
Unidentified high handle bars
Leather hand guard on throttle side (as 502)
Rickman-style chromed dual pipes
Dark green petrol and oil tanks
No "Triumph" logo
Bates-style seat similar to 502 (as 502 but not 141)
Rear frame hoop bent upwards (as 502)
Bracket welded to rear frame to support seat (as 502)
Braced scrambles-style foot pegs with plates behind (as 502)
Thicker 5/16" rear brake rod re-routed inside frame/shock (as 502)
Pre-unit brake pedal operating via slot in engine plate (as 502)
PRV with return line back to oil tank
Throttle cables running under tank
Black shocks, no shrouds (possibly as 502 with shrouds removed) (as 141)
Conclusion
It's not possible to be certain, but on the balance of probability, given the similarities between all 3 examples, it's extremely likely that these are all variants of the same desert sled, originating from 1963 T120C TT Special DU1683. I have never seen any photos of McQueen riding a 1963 Bonneville desert sled other than those numbered 502 and 141. It's very likely that #141 is #502 after some hard desert riding use, with a few modifications: heat shield on pipes, shrouds removed from shocks, different skid plate/engine case protector and seat. DU1683 shares a large number of similarities with both #502 and #141, though it has clearly been re-painted at some stage, had different exhausts and handlebars fitted and quite possibly another Bates seat (these were plentiful in the '60s and early '70s). Smaller changes such as the rerouting of the throttle cables under the tank and the addition of a later Magura brake lever have been made.
It's highly unlikely that the current paintwork on DU1683 was completed by Von Dutch. It has none of his hallmark pinstriping or even a logo and there is no evidence to support this assertion. It is quite possible he was responsible for the original paintwork on #502/#141, which seems to have been black from the colour photo and not dark green, as described in "Cycle World".
I don't believe there's any doubt that DU1683 belonged to Steve McQueen and it has all the hallmarks of a Bud Ekins build. This style of desert sled was not unique and many similarly-styled Trophies and Bonnevilles would have left the Bud Ekins shop in 1963/64.
McQueen probably did not use this bike much beyond 1965, when he obtained his Trophy-engined Rickman Métisse. At some point it has been modified with high-level twin pipes (these were not common in 1963/64) possibly resprayed or fitted with another tank and seen some use before being sold as part of the McQueen estate. Once the Rickman arrived, the old TT Special desert sled was probably not used much - the overall condition is good, for a desert sled of this vintage, suggesting that it didn't see much action beyond the first 2 or 3 years of its life.
This is my conclusion, based on the available evidence. As it is at the moment, I do not believe this DU1683 does justice to it's former incarnation as a Bud Ekins , but seems to have been evolved (either by design or chance) into a poor replica of McQueen's Rickman Métisse. Rather than just preserve it as is, to me it would make more sense to return it to it's former guise as it was when originally built as a desert sled i.e. to the condition it was in as bike #502 in the "Cycle World" photos, not long after leaving Bud Ekins shop. In its current guise it looks more like the kind of sled which was popular in 1966-67.
There's a wealth of information contained about its specifications in the "Cycle World" article and some good photographs. Most of the modifications described in the "Cycle World" article can be see clearly in the auction photographs for DU1683. It already has most of the modifications and it would take little effort to return it to #502 guise. The frame looks to be in good condition and it would be a pity to restore it to an inch of its life to concours spec. Rather sympathetically restore it retaining as much of its original patina.
Ace Classics from London are embarking on a project to build a replica of bike #502. I'm sure it will be very good - but they won't be using a 1963 T120C TT Special as a donor, and it will be no more than a poor copy of the original, when all's said and done. Nothing can compare with the original, and the current owner is in the unique position of being able to return this historically important motorcycle - which includes most of the modifications originally made in the Bud Ekins shop and described in the "Cycle World" article - to its former glory as it was back in June 1964, for a comparatively modest outlay. I think it would be an absolutely fantastic project to do this, then publish an account of the process in one or more classic bike magazines and ideally loan the finished product to a museum where others could enjoy it. From an investment perspective, such an approach would be a winner, really raising the profile of this special machine! (And the owner needs someone to photograph it and write the article, I'd be happy to oblige!)