Well, the Chevy II will have cheap(er) parts, the S-10 could have several different engines.
However I think a 2900 would be your best bet, you could use the 4L60 out of a Trail Blazer, Jeremy should be able to program it up for you.
A small turbo, say a TD04-15 off a Volvo at roughly 10PSI, with a good charge cooler should be impressive .
