I friend of mine has a 2003 F-250 with the 7.3L Diesel for sale that I am going to look at tomorrow. It has 75,000 miles on it, and I know it has had meticulous care (he is a retired heavy diesel mech...
If that thing goes on the market and it's as clean as you say it is, it will be gone on the fist phone call.
BUY IT NOW!!!!!!!!!!!! (or it will be too late)
Like Just said, wiring and CPS. Oh and the tranny's are pretty crappy. But you can bullet proof them and the engine will run forever. You will wear everything out in the truck before the engine quits.
Oh and as far as power goes; you can tune them up pretty hot and they will be fine.