[The Fixer]

I've never done a header swap on a thirdgen, but if it's not a complete biatch of a job to do you might attempt to swap. However, rusty bolts snapping in the head will suck for sure, so if either set has been together a loooooong time, it might be worth it just to leave it alone and buy new headers when you swap in a new motor. Nothing like an engine bay full of clean, shiny parts!