In some ways you are correct, but there is a point that is just too big that there is insufficient vacuum velocity through the venturis to get proper fuel suction and you end up with a flat spot or stutter until the revs come up...You could also always have whichever carb rejetted. You could get a 390, and if it's too much, have it downjetted some.
I am sure the right answer is out there, still time for me to find it!
Luke.