b16 block with gsr is a bit backwards... in terms of power anyway. you'll probably check in a bit under the b16 stock rating of 160 with the gsr head.
usually, you do a gsr block with a b16 head for the poor-man's ITR set up.
assuming you're ussing that p28, and stock gsr manifold, you'll not be able to operate the IAB's on the gsr mani. get something like a skunk2 intake manifold and not worry about it. looks like it's not there anyway, so just get an aftermarket gsr unit without the iab's.
based on completeness, you'll need some belts and stuff. is ther an alternator? exhaust manifold. timing belt, probably more misc stuff.
I'd suggest assbembling it all before you go in the car, trans and all.