I have a 2500 AV, with the same runing gear as the 2500 Burb, 8.1, 4sp Auto M32 Tranny, and 4.10 rear end. I have done a number of bolt ons, and I love the truck. It has even beat a few ricers. The only thing it does not pass is a gas station.
If I were you, and I could get away with a 6.0, I would get a 2500 Burb and the 4 Wheel Steering. WAY COOL! Anyhow, either 2500 Burb motor, 6.0 or 8.1 will do you just fine. The 8.1 will do you much better when you upgrade.