600 hp is doable. It is a bit of what you are willing to do or spend to get there, but it's not rocket science either.
I think it's also worth noting that headers definately work. You'll spend a lot of $$$ on other areas of the build to make up for what you're losing by not running headers.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
