Stock rods, crank, and Diamond pistons will be good to just north of 700RWHP. Actually even more than that, but I think 700 more than covers the 600 that you are shooting for. That will save you a lot of money.
I agree with hissman..
and just go with the matching diamond rings, clevite makes a good bearing, and all arp hardware.
Diamond pistons and rings, stock Manley H-beams and steel crank, Federal Mogul bearings and don't forget the ARP main and head studs. Fastners are just as important as the parts they secure.;-)