I was in the same boat about 3 years ago. I wanted 600+ but I wanted to be able to drive it too. I took the drive it option: stock bore, stock stroke, 9:1 pistons, iron block, iron heads, roller cam, cast manifolds, curved distributor with a race carb made 511 hp, my crappy 750 holley made 498 hp. 600+hp is great if you line up with all the high-end new muscle but think about all the extras that come with that much power...i.e. more money into the trans, frame twist, rear end etc. Those were the extra choices that kept me with a semi stock hemi as opposed to a 600+ street killer