What model is it? F-250, 350? Single wheel or dually?
The miles don't scare me, but be prepared to do some repairs. I've owned 3 7.3 trucks, one has 314,000, the next had 168,000, and the last has 194,000. Check the front end out well, tie rod ends and ball joints will probably need to be replaced. Try to start the truck cold, at that mileage you may begin to have injector oil flow problems. I replaced all 8 injectors in my '01 at about 193,000. These engines run hundreds of thousands of miles in International light and medium duty trucks, they're tough. I would be surprised if there are any major issues deep in the engine. Check the oil pan carefully for rust. To remove the oil pan, you have to pull the engine. Expect some oil leaks, most likely from the turbo pedestal. There are 4 O rings where the turbo meets the mount that leak. Crawl up on top of the engine and look at the back of the heads, you'll see two pipes leading to the turbo from the exhaust manifolds. Check where they meet the turbo for exhaust leaks. It's not an expensive fix, if you can do the work yourself.
I can't comment on the transmission. I sold my automatic 7.3 when it had 168,000 miles for other reasons. Transmission seemed alright, though.
If it has the electronic shift 4x4, make sure the automatic hubs work. They probably won't. They operate on vacuum, and there's an O ring seal on the back side of each hub that goes bad and causes them to not work in automatic mode. You should be able to lock them by hand, though. Replacing the O rings is easy if you're mechanically inclined, lots of write ups online to walk you through it.
The price doesn't sound bad at all, if it's in fair condition. Do you want the utility body? The truck frame is slightly different from a pickup bed truck, so you won't be able to swap it for one without some serious work.
