Better heads

engine quest heads would be the best approach...

can get them with drilled for LA intake manifold also...

I dunno.... Aren't those still a bit big for a street 318? I think to really get the most potential out of those heads you'd have to do a bottom-end rebuild with flat-top zero-deck pistons for compression/quench and beefy enough rods, etc. to handle 6500+ RPM.