The turbo is the main part that will either give you good power or limit it.
Stages dont mean anything to me. There is no-one who determins what stage 1 is compared to stage 5 etc. Idealy you want a 4x4 comp wheel and housing with a .48.
running 18psi with oversize valves on a cvh would make 230bhp.

Next is that 803's wont run 300bhp on an 8v and top out at about 270bhp obviously depending on how good or bad the head is.

Ive seen lots of dash's done by you now, so have no worrys sending custom your way as i know it will be a good job done.