I think the 2.5L "Iron Duke", which was the base engine in a lot of those trucks, has the standard Chevy V-8 bellhousing pattern, which is shared by the '63-up straight sixes as well. The very early S-10's (at least one 1982 model that a previous employer bought new) had an Isuzu four. Don't know when they started going with the Iron Duke.
The 2.8 V-6 has a different bellhousing pattern (shared by all of the GM fwd fours and v-6s, and semi/partially by the Cadillac Northstar V-8)).
I think you would be challenged by the length of the engine plus possibly hood clearance problems, not to mention smog compliance.
I have a clean '97 GMC Sonoma with a bad 2.2L four (Cavalier engine). I'm thinking about swapping for a 3800 V-6 from a late model Camaro.
