The pistons mentioned and headers won't get you to 400 but with a good cam you can get more than you have now.Basicly 4 bbl,cam,pistons,headers and high flowing heads but thats not cheap so pistons headers and cam is your best shot.
Too bad I did the opposite and went back with a stock rotating assembly without thinking about piston changes until I started doing in-depth research for gaining performance out of the little 318's. My setup includes: Edelbrock 750cfm, Weiand Action+Plus Manifold, Comp Cams XE262-H, 2 1/4" Exhaust w/ Summit 4" Glasspacks (stops at crossmember), Electric fan & fuel pump, Mallory Distributor, Summit Street/Strip Coil... Hope to have decent power once I put it back together in a few days. Next in line will be having work done to current heads or finding a set of the 302 casting heads.
