Blow through with vacuum secondary Holley Carb.

Not disagreeing with you at all because I don't know for sure, but that just doesn't make sense to me.
Wait a dang minute, this is why those boost kits with the entire carb inside a pressurized box works, correct?

I did the same thing! wait, no, yes, no... no.. yes... wait. Damn.

Yeah, that's why they make the pressure cookers. Keeps the float bowls and the vac actuator all seeing the same thing. It should work. But tuning it? No idea. Carbs aren't my thing :D