SuburbanSwapper

So I'm fairly new to all this, but I have a general idea of where I want to go with my build. So far I'm looking at pulling an LS1 from an older Tahoe or Suburban (2001-2005) and to go from there. I know that I'll be needing a wire harness which I've found one from Painless Performance that should work. I also plan on swapping to a Monster brand 4L60E transmission. Other items include the newer style condenser, a new radiator, and gauge cluster to accommodate the new engine. So what else am I missing? Will I be needing a new computer to make the engine work? Or could I pull it from whatever donor car I get the engine from. I'm decently skilled at wiring as my dad and I wired a 69' Camaro ourselves with just about no instructions and lots of trial and error. So pulling the existing wire harness apart should be too big of an issue for me. Any suggestions, tips, or general advice would be greatly appreciated.