55-59 truck V8 would likely be the best option. As said, the mounts are different, but I would think you could make it work alot easier than cutting everything out and starting over. Do not try to build one of these trucks without some sort of crossmember in that area of the frame.
60-62 have a hydraulic clutch fork on the passenger side, at least for the sixes, so I assume the same for the V8's?
You will most likely need to move the radiator forward also.
You will need to buy or make side mounts for the engine, as there is no provision for mounting under the timing cover on the 250 engine.
