I have to say that the 5 speed has been a bad idea from all that I have heard. I have swapped mine over to an Automatic. Something I never thought I would do, but the 4.9 with the caddy's electronic shift and overdrive is the way to go especially if your engine has one already attached like mine did.
The 5 speed will add a lot more cost when doing the swap, and again during the owning period of the car, since as everyone has said, it will go through clutches quite often. If you are going to go with the 5 speed, I have heard that the Isuzu is just as good as the Getrag. Might look into that and make the decision for yourself.
The wiring is hard work, and takes a while, buut the actual understanding of it, is becoming more and more clear as more people do it. When I first wanted to do this, there was a lot of open ends so far as the wiring went, but now there are a lot of guys out there who have it figured out, and can help trouble shoot as you go.
All swaps are hard, but they are very worth the time and trouble, and this one is one of the easier ones out there I think. Just do it and the answers will come as you get to the individual parts of it. This has been done before, and the forum will give you all the answers you need.