Blow through with vacuum secondary Holley Carb.

Except the 'vacuum' is just a pressure drop as the air accelerates through the venturi. So long as the whole carb is pressurized, it should be fine. It's the backside of the actuator that needs to see the same boost as the carb throats.

Doesn't mean it will work 'fine', but it should work.

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?