i agree with every one else. head work and cams is un-needed for 300whp. just do pistons and rods with arp headbolts and stock headgasket and throw it back together. spend that money on a clutch, fw, lsd, and 3" exhaust. and no need to rev the piss out of it, 300whp dd is very easy to do. a simple kit like toms with a turbo like a gt28rs will be perfect, and just like tom said a precision is a reworked garrett. the 2k IM is a one piece unit instead of being 2 piece like the newer manifolds. mine held 27psi for over a year no problem.
good luck with our build, your in the right place for plenty of useful advice. most of us here have made 300whp lol
Turbo Turtle Garage
Mig and Tig fabrication, engine building