What exactly do you want?? thats the real question, if you want a good ol 4.2 with 100-150hp then go the silvertop for the price + a dc3 pump. If you want 150+ then the factory turbo hands down but you will need a new turbo and pump.
Are you looking to do the conversion yourself or paying someone to do it? Just wondering as it only cost me $5300 for my whole conversion including the motor to do it myself. Diffidently +1 on swapping to the 4.1 diffs ive just down that. 4.66 are fun but for highway cruising way to high in the rev range.