318 complete combo suggestions...

It’s a matter of expense to fix a problem that’s not really a problem or running what ya got and making due with it and enhancing what you have via of camshaft to help and minor mods to what you already have.

Enhance what you have at a relatively inexpensive cost or re build and modify everything at a much higher cost.
There is a larger return in rebuilding and modifying everything. But it is MUCH more expensive!

Your doing a total rebuild with aluminum heads? I’d skip the flat top KB slugs and go right to the dome slugs for more cylinder pressure and a nice cam.