Assuming your 350 small block Chevy is using flat top pistons with valve reliefs, a cylinder head with a smaller 64cc chamber will immediately help by adding compression. If your budget is tight, I’d suggest a set of affordable iron Vortec heads. These heads flow much better than almost any production Chevy head.

A head with 180 or 185cc intake runners will work well on a typical 350 Chevy street engine that makes 400 to 450 horsepower. If it’s a 383 stroker, you can probably go with 200cc intake runners. Putting a higher flow head with 220cc runners on a relatively stock 350 would be going in the wrong direction.

In the article above, the author recommends either swapping to Vortec heads or using a set of Summit Racing aluminum heads for better flow.