Everything is 750 CFM until 1970, then in 1971 all Buick Big blocks got the larger 800 CFM Q-jet, some Pontiac too I believe. All you need to do is look for the bump in the outer venturi wall to know it is the bigger carburetor. You can do that by eye.
Thanx, so if a guy was to grind that hump out of there maybe a little more cfm or is there something behind that hump?
Absolutely not. That hump is there out of necessity, maybe a passageway or something. It wouldn't be there if it didn't have to be.
