350 5.7 Swap in 1966 Fleetwood

I am having the original engine sent out to be rebuilt however that will be a long process because of cost. However, I have a 1994 GM truck with a 350 small block in it. I was wondering if it is possible to swap in the engine and trans from the GM truck into the Caddy temporarily. I don't know if the engine can run without the wiring harness or if I can just use the engine bare bones since the old car doesn't have a lot of wiring, to begin with. If any car guys have worked on this engine before it would be a lot of help.