318 and which cam?

Could shave the heads for some cheap compression. Then you would need to shim rocker shafts. Just an idea. I did this with a low compression 340. Shaved the heads and ran thin head gaskets to get 9.5:1 out of it with a Lunati .480 cam, LD340, holley 750. Huge improvement over stock. i bet all together was a good 50HP gain