1973 340, want more power.

I think we are getting off track here.

Before you start throwing parts/money at a problem that doesn't exist. LEARN about your car. You don't even know what camshaft or rear gears you got. Basics. I know exactly how many miles my cam has on it. How many times the oil has been changed. I know my rear gears and how many miles are on them. I can probably even tell you how many fart's I've drilled into the seat.

KNOW everything about your car. Then you can know what to change. Can't know what's mismatched until you know whats in there. Otherwise it's like trying to bake a cake blindfolded and without the recipe.