[Graham]

I've just done a Mille Miglia 1940-1955 list

250 GTO 64 was in the Targa Florio
Porsche 550 Spyder was in the Mille Miglia
Lola T70 was Targa Florio
GT40 was Targa Florio

But the Ferrari 250 GTO was also in the Tour De France 1963-1964, so that’s where it would probably go 
And I make the rules 

There will need to be some intentional segregation of car types to make it a good balanced competition.