The 4.8 would be ok, but I would price a 5.3 (327) before buying. These guys are probably hand picking their engines from local salvage yards in the Gilroy, Morgan Hill area according to mileage. The 4.8 and 5.3 should go at a much cheaper price than the larger displacement LS engines. The LS engine would be a plus for the value of the truck later on too. Sounds like a good way to go if they will give you some installation and start up support.