What's his budget? I suggest a late model 4.8 or 5.3 Generation III V-8 and overdrive automatic from a Chevy pickup or Tahoe. If he is satisfied with 6 cyl power, then a late model V-6 EFI and OD trans from an S-10. It's hard to beat the late model V-8s for a combination of power, drivability and fuel mileage. And once you have them in and running, they are ultra dependable and low maintenance. He should be able to get a V8/Trans combo for $1000 or less if he shops carefully. There have been quite a few put into 50s-70s pickups already.

Pat