if a holley list 4780 carb (800 cfm dp) was ever used on a production car? or was it just an aftermarket deal? i thought it may possibly have been used on a hemi from the late sixties but i dont even know where i got that idea.

it's an aftermarket deal only AFAIK. Ever seen a 4780 with an automatic choke?

All of the Hemis I've seen had two Carter 4-bbls inline. Athough, I don't know about the factory race cars.