Holley/Demon Carb stumble

Found the thread with the metering blocks cutaway
Page 4
Power Valve Selection: The Definitive Answer

So i'm trying to get rid of the pore transaction with a smaller air bleed. Idle air bleed? just rears or all ?

I have a 6.5 Power Valve in and am thinking of going with a 10.5 that i have on hand.

So here is my question. do i plug the PV and find the flat spot?
Do i use vacuum gauge and set it just above my starting line launch rpm or do i watch the vacuum and put a power valve in just above whatever it stumbles at.???