I believe you are backwards here. When four barrels were first introduced in the early fifties, carburetor flow benches (or whatever they used to measure a carb's cfm capacity) couldn't handle the added flow of a four barrel, so they were measured at less pressure. Result is that a 500 cfm two barrel flows about the same as a 350 cfm four barrel.
FWIW, I have twin Holley-Weber carburetors on the flathead six in my 49 Dodge. In other words, four barrels vs. the original one. I just put them on for looks, but I was pleased to find out that it made noticeably more power, too.
You can throw out all the formulas you like, but I know from experience that even an otherwise stock 273 will make more power with a small four barrel than with the stock two barrel.
