I'd say keep it simple
Built trans (not ATS)
Lift Pump
EGR Delete w/ LB7 up pipe
EFI Live
Turbo (twins, fixed geometry or a badass Danville 68R vgt)
Injector nozzles (40% over +)
That will be an easy 600hp with a healthy CP3. IMO no need for billet shafts, flex plate, head studs or...