You could probably find the motor from a Durango or Ram at the junkyard. The problem is that you won't know the condition of the engine and many junkyards sell at prices that are way too high for what you get in return. You can buy motors, even complete, from Autozone. That would be less than a high-performance crate motor. It may be cheaper to find an old truck or Durango that you can take what you need and sell off the remaining parts.
thats most likely the way Ill go. I got a 89' (4 x 4) w100 truck with a fuel injected 318 with a dead a727 transmission. Im removing all the computer junk and dropping in a 360 with a 4 barrel thermoquad. The problem is I dont have a another 1/2 ton truck to be able to haul a engine back.
Yes Im aware a magnum series engine can go in but, I want this truck to be old school. This truck has one purpose and thats to drive a total of 4 hours a month to get up to the farm through all the low water crossings, hauling trailers back and forth. Its not a everyday driver.