What paspecops said, the 6.2L is way underrated. It doesn't make the power of a 5.9L Cummins or Powerstroke, but it was never meant to. Even in a 1-ton truck with gears for hauling, you'll still get at least 15-18mpg empty, and 12-15mpg with it loaded as full as you can get it. I think in 1986 you could get one from the factory with a Banks turbocharger and special gauge package - that's definitely the way to go. These drive like a mildly warmed-over EFI 350 and deliver twice the fuel mileage.
If you don't want a diesel, my recommendation is an '87 or newer Chevy/GMC pickup with EFI 350. It's not likely to need repairs, and if it does troubleshooting is simple and parts are inexpensive.