The article tells us that Heppenstall was a well-known Crosley specialist, and it is more than likely that he built his own car. The puzzle photo clearly dates from the late 50s/early 60s when H-mod cars were being built, and I believe that the puzzle photo is of a completely different car, and not the Voigt car which he purchased in the 00s. He probably bought it like a lot of older people, to remind himself of the "old days".
I'm convinced that they are two very different cars. Mind you, the puzzle has been solved anyway!
PS The steering rack came from a Renault 4CV but this still doesn't explain why he decided to make the car RHD for racing in the USA. Seems a bit odd to me.