FM1200, you get my YAY for the day. A voice of sanity in the great carb debate.
You are ABSOLUTELY right.

The only thing that i would care to add is that when one calculates the max air consumption, one must remember that this is a theoretical maximum based on a volumetric efficiency at max revs, of 100% which few engines of our type can approach. I think that The Chrysler hemi's come reasonably close, but the're legendary, & i'm biased, so we won't count them.

To get the true volume of air, the formula must be adjusted by figuring in the percentage of volumetric efficiency.
For stockers this figure can be about 80% with souped up examples on the street running at something like 85% & the real hotties looking at about 90% AT FULL SPEED.
Lets see, a 1200 is 71.5 cubic inches. Now my formuls is diferent, but gives the same result. It is CFM = RPM x CID/3456 divided by VE

So our example is a 1200 at 6000rpm Thats 6000 x 71.5 = 429000, divided by 3456 =124cfm. Now divide this by,... lets say 85% [VE] for a street engine like my GX, & we get about 105cfm. That's a realistic carb size, or maximum airflow for THIS EXAMPLE.
Now we can round this number up or down a little to fit in with a carb[s] capacity that we can buy & feel confidant that we are not short changing ourselves & not reducing performance due to overcarbureting. I could cope with an increase of 5% to 10% on this number, but it will not really yield any noticeable improvements.

Lets be realistic blokes, how many RPM does YOUR street engine see for 95% of it's running life. Mine is red lined at 5,500rpm, i run stock GX carbs, & i still have the same engine 23 years later.

FM1200,.. you the man.
Chris