400 low buck dont give a

Well,the compression is the issue. I'd buy some hyper pistons to get it up to 9.5 or 10:1. You really need to address that issue or the motor wont run worth beans. You could still do a shade tree build on it despite investing in pistons by reusing all the stock rods/crank and heads etc. Really what seems to add big $$ to a motor is machine work and new aftermarket parts.

Rebuild the heads yourself by using some seat grinding stones,and sleeving the valve guides. Then hand lap the valves in.