The drive train I swapped into my Tracker had 30,000 miles on it, but had been sandwiched in an accident. The water pump was very stiff and felt like it was dragging, so I replaced it. My timing chain and guides had no wear, so they were not replaced, but new water pump was much smoother. With motor on engine stand I I had everything except timing chain swapped out in one day. Having been squeezed put stresses on water pump and front timing cover, and the cover cracked when tightening it back down (I had found another motor with a spun bearing for $50 so had that to replace it).
As your motor is running good, I don't see you needing parts for it, but if you do, those parts are available.
As for changing out the timing chain, unless you have a mechanic that has changed out a Suzuki V6 before, I would be more confident in your doing it with photos and a FSM, than just another good mechanic. (And then I still have the spare motor to double check alignments for you). I also have both 2003 XL7 FSM's you could use, I do think the wiring is different, but mechanics of motor should be the same (I think shipping books is very reasonable).