alright guys/gals heres the deal.

i've got my 98 1500 silverado that needs an extra geddy up and go for the road and for the drag strip.
its got a 5.8L vortech(rebuilt not too long ago 34k) all manufactured parts which isn't cutting it out for me.
i've been lookin all around and have found estimates for hp on my truck to be 250bhp & 325rw and i want to get around 400hp & 475-500rw
i'm not too sure wether or not if i should get an engine mounted or lower mounted turbo system its a bit ify on both sides.
room is a problem in my engine compartment and so on and so forth.
i know i will need a tune up to get around that hp, new rods gonna try to get some forward mounted shorty headers(becauseofspace) and any and all other things i need.
i know buying kits are cheaper but i want this a custom kind of fit for my truck.
i know that i need a .64 a/r from end of header to hot turbo side but not too sure what i should get.

Any points,anyone or anywhere ya'll know of that could help me out?
any personal experience?
anything will do.
thanks.