318 was from the get go meant as a reliable engine for daily transportation.It responds to performance mods as good as any engine.Personally i would use either "302" castings or magnum heads.With magnum heads you would be o.k as cast for performance,"302' heads ported work great and still maintain shaft rocker system.Oh i'm back after several yrs use to be waynebo or w5365,can't remember:burnout: