340 carburetor selection advice

I read that you have the RPM intake employed.
I’d run with the above post by Oldmanmopar. The carb he recommends is a very good one and isn’t a hair raising experience to tune. Just start with the basics and move on from there IF even needed.

Going through your combo, I myself just don’t like the cam very much. Other than that, the 750 won’t give away low speed torque. Everything should improve. A larger carb is not an automatic penalty for power loss.