82 silverado engine/tranny swap

hey, i inherited an 82 silverado, but the tranny started slipping, and eventually wore the rod bearing. so the truck has been out of commision for a while. it currentally has a 78 350 and a 3spd auto. i came across a cheap 77 oldsmobile 350 and transmision, and i was wondering if the engine and tranny mounts would match up with the ones on the truck. and if there are anymore problems that i would come across in doing this swap. thanks