4.3 vortec to ls1 swap

Hey, so I have a gmc 1500 Sierra that came with 4.3 vortec, I came across a complete ls1 from a 98 trans am with trans and harness, im starting a list on what I need to get/do to get ready for the swap, I hear swapping my rear end to a 8.5 and throw some 4:10 gears should be one thing, what else do you guys think should be next to do or get

Ls1 swap obs silverado conversion

Im in the saMe both as you only mines is a 5.3. I think fuel pump would be a big one to add to the list