Just make sure you can dedicate yourself to maintaining it. You gotta do the routine maintance or it will die. Especially the timing belt and the tensioners for it. I just bought a chiltons(their not the best help but they have needed specs and diagrams) and it has helped so I would suggest getting one of those. Their very needy motors but if you treat them well, they will treat you equally well.
Also make sure its a early monte carlo or a grand prix or else the wiring harness wont plug into the body harness..... Forgot the question you asked and for now I'm just using the 4T60E that the engine came bolted to already until I find a 6 speed.