The drive line is the same as a 02 and up GT, if the Mach is a 5 speed then you already have a forged crank, its good for more the 500hp, if its an auto then around 500 is right.
Pistons and rods are pretty much a must for 600HP. Axles and Diff too. But like said above, its how you drive it. You can do a Magnum T56 swap or a TKO600, them trannys can hold a bunch.
3.73s and Brembo's
6 speed gear jammer, thats all!