Leigh,

According to the Holley Numerical Listing for their carbs the 4150 - 4346 unit is 780 CFM.

http://documents.holley.com/techlibrary_carb_numerical_listing.pdf

It is near the bottom of the first page. This carburetor was used on numerous Chevy high performance engines including the L78 396/375, the L72 427/425, the DZ 302 in the Z-28s, the LT1 350/360 and the LS6 454/450.

In addition to full size cars, the L72 was also offered in the 1966 Corvettes. They are great motors, I am on my 3rd one now. An original 68 Biscayne, my current 68 Biscayne tribute car and one transplanted into a 1967 SS Chevelle.