Mark,
If the bike is a CR and not a CB750R it should be no problem identifieing it as the frame is a dead give away.
The only problem then is which of the four frames is it.
The artical has already said that two of them got shipped to France for endurence racing.
The frames would no doubt have numbers, but would the riders remember what number frame they rode ?
I seem to remember, back then any member of the public could claim the winning bike if they had enough money, it was one of the rules of the meeting. Bikes did'nt disappear they got bought by wealthy collectors.
The big factories had their own people ready to buy their own bikes back before anyone else got to them.
It would be nice for the reserchers if it did turn out to be the Mann bike, personaly I would plump for it being one of the endurance bikes.
Sam.