Looking to boost the power of my 318

This is always the dilemma. Your going to have to pick your poison. Weigh it out. Going the Magnum head route will cost more in extra parts to make it work, but the 1.6 ratio is a perk. I myself would look at the after market heads. The head flow is much better for what you get vs. what you pay for.

Sorry to see you short sell the 302 head. Do not think the head doesn't flow enuff to do well. It does and ported it'll do much better than you think. They port out very well and are capable.