Just from bits and pieces of articles I've read plus playing with software dyno.
Someone with a dyno should be able to back it up. If you put an engine on where the dyno verifies it's using eg.. 600 cfms when you bolt on different carbs say 550, 650, 750 etc.. the engines vacuum should change to a value where each carb would become a 600 cfm.
I just found this article I skimmed through it's basically saying what I'm saying.