Be careful of the ones that were in offroad/construction equipement. The governor setup on those engines are different from "automotive" applications. The Frito Lay van motor is an automotive application (CPL858), which is what you want. An automotive type has a governor that works well for throttle on/ throttle off use. When driving a vehicle, you accelerate and deccelerate often, and it's governor is set up to do that. The offroad applications such as construction equipement generally are governed like this... ... ... . you move the throttle to WOT or near WOT and use a hydrostatic transmission to control the speed. The governor setup on these engines do not "respond" fast enough to use them the way an automotive application requires.
Avante' Salvage that BJ mentioned gets about 2500 dollars for a 4BT with your choice of turbo 400 or sm465 transmission. All of his are CPL858 automotive applications.