Why do you say rethink the 302s? They are a good head to use for the 318 IMO. If I was building a stroker or something with larger displacement I would go another route, but it is still going to be a 318 with whatever cylinder wall clean up I need.
I had the stock 302 heads on the car for a little bit before I tore it down just to see how they felt and they felt pretty damn strong, lots of low end. I plan to put bigger valves in them and have them mildly ported. Along with more compression; decent pistons and 0 deck, I am looking for 375-400HP at the engine, which I think is very possible.
ocdart, thanks for the recommendation, I know there have been some other good 318 builds, one by MM a while back and another by Hot Rod, and maybe a third. They are all good reads and I will have to check this new one out.