These LS engines seem to have a lot of versions of things that can be interchanged without going very far away from GM. One of my favorite shows is Engine Masters and they had a show one night testing the various oil pumps and showing what power they could require. I was shocked how many hp the big ones required and how much oil pressure they could maintain.
I had thought that the modern stuff would not need such serious stuff due to the ability to run tight clearances on light weight oils, but, I guess when one is pushing a 1000 hp, or more, that it takes a lot of effort to keep it from "rubbing". Wish I could start over with the LS stuff.