Ok, well if you want 600 on a single or on compounds. With compounds a small ish turbo even a hx35 or something is fine, then you need your under. Like a ht3b or something similar. Maybe a s470 or s467, very cheap to do almost as much as a nice single. Just need a piping kit which I can think of a couple companies. As for a bigger single for now but can still twin it a 60-62 mm of various companies is a good start depends how far you wanna go single. A bd product is always a good choice for ease and price. Super is a 60 I believe a killer is a 61.5/64 or 65 I think and can make good power. Over 650 horse on a cr. 63/68 is about as big as I'd go and still plan to twin later and even then you'd need a cam to take full advantage and with a
Matching bottom your looking to make 700 or so horse potentially with probably a s475 or larger. And finally 600 on a single, I'd get a 64/71 or something very similar, of some sort. A 63/68 has been claimed to make 600-650 but that's not so easy on a 12v and the 64/71 will defiantly do it if a killer can make 660 or something on a cr. current experience with a bd special 64/71/14 is it's great. Made 405/847 on a nearly identical truck as yours except no dv, and stock trans, and keeps up with my very fast spooling he351 and that's stock fuel stock everything basically but minor bolt ons and tuning. Now looking to sit around 425-450 / 900-925 with a cpp race trans and 191's. And next summer with cam, head work, injectors etc looking to push 650 or so on fuel. All on a single bd special that spools great. So that hopefully gives you a little idea of possibilities. There are lots of options in various sizes and mods and stuff from like ed or htt or ats but in the end most are not a hell of a lot better than a near box turbo. Trying to get the simplest set up is the best and cheapest route. With my cam I plan to run a single 464 almost purely that I can get a box 464 for 750$ with 360 bearings and milled for a he351 flange and still have money for an external wastegate and a steed speed manifold and all that will cost as much as like a 64/71/13ss or something from htt or a 63/68 from ed. And just a bit more than a bd special or killer which are a bargain at 1600 ish for a full kit. So don't exclude the simpler methods.