Here is an easy way to TRY and explain it. I am building a hot street 440 with a six pack. The carbs are here now.
The venturi and butterfly measurements of the two 500 cfm two barrels carburetors is exactly the same as the customers current 850 four barrels.
So whatever the 350 carburetor would flow compared to a four barrels is the only gain.
I will make a post later about the intake, porting, etc
Keith