if you use your d15 block, definately do new:
forged pistons
forged rods
new rod bolts
new main studs
new main/rod bearings
get low compression pistons if you plan to boost, and it help to lower the compression by using a d16z6 headgasket. as for the head, get it machines to about .30 and port/polish. ive done a d15b7/d16y8 mini me before and used a dsm 14b turbo, jdm sport front mount intercooler, greddy S blowoff valve, ram horh turbo manifold, blox intake manifold, tuned on chrome with a apexi safc2 to run 18psi. used eagle ibeam rods and low compression pistons, didnt sleeve the block, jst updated the internals and bolted on the parts. id reccomend going the whole nine yards though if you can afford it.