Colby - in 1957, Chevrolet used 2 different WCFB carbs on production engines, both passenger and Corvette, 2505s and 2555s. These numbers you will find in many references. They each flowed approximately 380 CFM.
But in 1957, Chevrolet also built racing 283's. These used Carter WCFB number 2493s. This number you MIGHT find in a few references, but it exists. And Carter published a flow number on this carburetor. It was also 380 CFM.
I have asked a number of folks this question, with absolutely no disrespect intended: does your 283 require more CFM than the racing engine built by Mr. Duntov?
Jon
