All the stock street hemi carter carbs I've seen, 1966 up to 1971 all have the smaller primary throttle blades than the rears. I'm thinking all of those carbs. flow around 600 CFM, both the front and back carbs, maybe not
When Mopar put the new E series Carter 3705 AFB on the 1964 Max Wedge motors that shook the Hi Po world up and made those cars with those motors noticeably faster than the 1963 motors with the smaller 3447 ABF carbs
G.M ended up dropping out of the Hi performance cars wars in the spring of 1964 is what I'm remembering now. Ford had brought out the 427 ford Thunderbolt Fairlanes and those cars gave the M. W. B body cars a run for the money so Ma Mopar came out with the 426 Hemi motors for racing only in the first part of 1964 for both drag racing and NASCAR racing back then