The story as I understand it from a couple guys who do concours restorations on Buicks is that yes, some 1971 455 Buicks came with 800 CFM but that not all of them did. So, you have to check a '71 to verify if it is 750 or 800 CFM. GS455s weren't the only Buicks with 455s, the Rivieras, Centurions, LeSabres and Electras could also have them.
So, if you have a '72 or later Buick carb you will likely have an 800 CFM carb, a '71 must be checked and a '70 will be 750 CFM.
P.S. Of course my sources could be incorrect.
1968 400 Coupe, verdoro green, black vinyl top, auto 1969 GTO Judge coupe, Carousel Red, manual 1971 Trans Am, cameo white, auto 1970 Buick Skylark Custom Convertible 350-4(driver), Fire Red, white top, auto 1972 Buick GS Stage 1, Royal Blue, black vinyl top, auto
