Why not? Like you said, the Caddy engines make great torque, they had to to get those land yatch's moving. I've seen a 73 Camaro with a 472 in it, and my friend had a 1970 500 in a S-10. That thing was unreal! Forget traction. 1970 was the high compression, big power 500. Had to put a body lift on it though to get clearance for the exhaust/steering. If you're gettign the whole car, there's a decent chance you can use the frame mounts that are in the Caddy, although you may want to look around for a BOP short tail transmission if the Caddy has the longtail in it.
BTW Vin, I always love messing with people when they are looking at a matching numbers GMC pickup, with a Pontiac engine in it. I've only seen a handful of them though, but man you should see people scratch their heads.