I don’t get this idea where someone wants to mod their engine but thinks their gonna get it at the 1st stab, instead that it might take a couple of cam swaps, carb swaps, gear changes etc… to get tailored to suit you.
I’ve yet to hear anyone state how much vacuum their engine pulls on a full throttle run when asking if they should go with a different size carb.
Because it’s stupid to worry about that when the carb is close to proper size for the task at hand which in this case is not WOT performance. It’s a secondary minor at best concern if at all.
What most people are looking for in there daily driver or mile hot rod is drivability first (response and mileage if that idea of mileage even makes the grey matter!) and good WOT second.
The amount of vacuum drop achieved is not of any real concern for most applications unless maximum results are your thing. The difference in a 1.5 to a 1.7 is a few hp at best. Something you’ll never feel and be very hard pressed to see at the track with a street driven seldom seeing the track car.
This, by you;
I think carbs should come with 3 cfm ratings the conservative 1.5 hg for stock and maybe add something like 1 hg for performance and 0.5 hg for race.
Is out of wack and dangerous to follow. This will for certainly lead to a poor performance tire not e in each class you listed. Been there, done that, seen it tested, seen it dyno’d, heard it from seasoned fellas.
Even @ 0.5 for a race engine is boarded line in some case, if not out right crappy. Full blown take no prisoners exempt from my descriptions above.
These are also not cfm ratings but pressure drops in the engine.