you'll be glad you're pulling it from a running car, as you can see where the parts go, keep track of fasteners, etc. It sure makes it easier to put it back together.
And, FWIW, I too will be getting the same heat from the Pontiac Purists, but it's worth it as the LS engines really are that great.
Did the donor car come with the 4th "IROC" style rim?