More carb tuning problems.

[Frank Messina]

Jake,
It appears you're closer to sorting this thing out than you might think. I'm not going to muddy the water but just clarify a couple points you raised. Drilling the throttle blades: This is usually only done when the engine has a really big cam (relatively speaking) and you have trouble getting it to idle properly without opening the throttle blades so far that they are now uncovering the transition slots which results in a huge off idle stumble. Drilling the throttle blades introduces air into the engine and allows the throttle blades to remain in their correct position. I'm not saying it's hurting you, just what it does.
Idle mixture screws: No they don't have to be the same all the way around. Starting off 1.25 turns out on the primary and .5 on the secondary is fine. Give the motor what it wants.
No Power Valve: If you run no power valve on the secondaries you need to jet up 9 -10 jet sizes to compensate for the lack of PV enrichment. So if you're 73 on the front you'll need to be somewhere around 83 on the rear, maybe more. I'm not going to make a prononcement here and say you should leave it out or put it back in as this is up to you. I've run my dragstrip cars launching at 7500 RPM's with, without and everything in between and you can make a case either way. For the street though, I prefer to run with a secondary power valve.
Jets: I might be off one number here but you're carb came from Holley with #72 or # 73 jets all the way around. That's you're base. You won't stray to far from there. HTH
Frank