600 Hp?
The 57s should get you to 600, maybe a little more, as will stock pistons, rods, heads, and ECM. The girdle is a good idea at that level, though. Bigger heads, and injectors will make it easier, but may tempt you to run in less than perfect tune. I mean, you can make more power by tuning what you got, or you can make more power by bolting on more stuff, but you make MOST power by doing both!