Rivera Boattail? would it be good for a project

well i found this 73' rivera boattail for 1000 the interior is great new carpet seats and all that the exterior is also in great shape but the engine is gone its has alot alot of miles and the the tranny is bad so i was thinking i could buy it and restore the tranny and the engine or i could get a better engine like a 350 from gm performance parts. so what do you guys think?