Alex on my thread serpentine belt configurations Ken listed all the GM part numbers you need for an LS7, but it should work for all LS engines, I ordered mine from gmpartsshop.com they were 1/2 the cost of going to a GM dealer. If you choose to do this, order all the GM bolts at the same time. It fit perfectly with lots of room, you will need to change the pig tail, I have the part number for that as well if you need it. The big hurdle is the belt tensioner you will need one at the top of the water pump I have designed and fabricated an adjustable one but I haven't yet installed it as the motor is sitting in the chassis in mock up mode. Once I know for sure it works If you wish I could send you the drawings or CAD file but there is a bit of machining involved.
Cheers,