adding to what brettstoner said here. seriously don't over look your supporting mods. on my first topswap build i had ZZP stainless headers, a 3" TOG DP with a 200 cell cat and an intake. that probably would have worked fine but it needed finer tuning and in the end i chipped a piston. on this build i installed a S1x cam and Ls7 lifters, also 90# springs and im still crossing my fingers