Yeah i would stay away from cheaper parts as the gte internals are better than some of the low end h beam rods. But Manley, weisco, cp, pauter, Carrillo, crower all make good parts for the application, having a good machinist check all your measurements is also a big deal, the strongest rods, pistons, and hardware don't help much when you spin a bearing.
Notice I said hardware, everyone wants to focus on rods and pistons but upgraded rod bolts, main studs and head studs are important too.
Cams seem to be if you are going to build the head then might as well go big.
For the trans I'm planning on useing a t-56 magnum either faceplated or with ppg dog gears in it.
Right now I have a built engine and no car because until I can figure out the obd2 situation I'm not buying an is300 that I may or may not be able to keep street legal, I may end up with a sc300 or do a full conversion to a fd rx7 or if I can't figure out anything better the standard old 240 conversion. I'd get a Supra and call it a day but the wife thinks they are hideous and when spending 10k on an engine alone without any grievance i can accommodate that one wish lol.