Hm. I can think of another one --- a '71 S with a 'special (2.4) engine' . . .
https://www.early911sregistry.org/fo...siffert%2C+911
https://www.early911sregistry.org/fo...-to-Jo-Siffert
https://www.early911sregistry.org/fo...hlight=siffert
I would think the 'production number' (1010437 on the dash) would be all the Porsche Arkive would need to tell you anything you wanted to know