From what i can read, im not sure if your bottom end will cope with 600-650bhp...or at least not reliably.
200block? has it been linered/long studded?
How much port work has been done to the head?

In terms of turbos... garret gt/gtx, borg warner, turbonetics, holset all do turbos they may suit your desired power level.
And i notice in your last post you are talking ported shroud on your turbo?- if you want least lag- dont go ported shroud.