[The Fixer]

Definitely keep the engine harness and all related wiring going to/from the ECM, as well as the fans, smog stuff, fuel pump wiring harness. I'd save the dash harness too. It might come in handy when you need to pin out connectors for gauges in a non-F-body if you go that route.

When we converted my old Monte to TPI, I got the complete wiring harness from the donor car - there were still tailight bulbs hanging off it! We took what we needed, and then scrapped the leftovers after the car was running and everything worked (gauges, Check Engine light, etc). IMO, you should keep the car around if you're swapping into a non-F-body until you know for sure what you won't need. Better to have extra crap laying around than finding out afterwards you needed something.