boring my 318

I read the responses twice and everybody forgot Duster Boy's original question. Most 318's came with 8-1 to 8.5-1 compression ratio. If the best you can get for gas is 91-92 I would keep the compression at or below 9.5-1.
How do you bump the compression 1-1 1/2points? New pistons with a higher
compression ratio would do the trick. Cylinder geads with a smaller combustion chamber will raise compression also. (like the #302 heads with the heart shaped combustion chambers) You can also mill the heads and or machine the block and also the intake (so it will fit).{I don't recomend} You can also install thinner head gaskets for a slight increase. Boring the block doesn't actually raise compression and neither does a different crankshaft. Those two options just force you to install different pistons with the ratio you want.