The y8 or the z6 are the best. Everyone has opinions about the both, but they are comparable. The plenum is bigger on the y8, but could run either no prob. 300+?? You need pistons, rods, head studs, etc.... stock head should be fine. A t3/t4 57 trim, .60/.63 will make that power, or a bullseye SPEC .70/.63. Its all abouthow much money you wanna throw into it.