After half an hour rolling around on the damp grass I decided to call the post-purchase inspection "done". Didn't find anything unexpected, but then again I had already poked around the truck before.
The frame has definitely been repainted, but it does seem to be in pretty decent condition nonetheless. There's a little bit of scabbiness inside the bottom of the framerails between the axles, but everywhere else I can get to with my fingers appears to be clean. Oh, and it does have a new roof.
I know it was parked in a damp spot so the axles and other metal items including the outer shell of the muffler aren't in great shape - fair amount of surface corrosion. OTOH parts of it are almost pristine, which is a weird combo. You can see some corrosion on the body but most of it appears to be surface corrosion on the body seams.
Oh, and it has some "issue" with the emissions system .
It'll have an appointment with a wirebrush, rust converter and some paint once the weather gets a bit better. I don't think it has been offroaded a lot to the frame doesn't appear to be filled up with mud. That's a nice change given how many TJs around here need massive frame repairs.
The current plan is to throw a bunch of rust converter at the surface rust, pump a bunch of Fluid Film or similar into the frame and coat the underside of the truck with with wax undercoating.
Assuming the brake lights work - wife's at work so I couldn't ask her to look while I pushed the pedal - it needs one headlight to pass inspection as I think it's got an iffy high beam. Everything else that's relevant for inspection appears to work.
Mechanically it needs an oil change, probably fresh oil in axles and transfer case (gearbox oil looks and smells fine) brake fluid change and probably some new pads and rotors. Given that the brake calipers also look like they've been parked on the seafloor for a few years I may just swap those out, too, especially if I managed to break one or more bleed screws. Oh, and the idler pulley for the serpentine belt also has a bunch of rust on it. Even though it spins fine I'll throw that one out sooner rather than later before it damages the serpentine belt.
I also need to steam clean the interior. When the PO got the truck the roof had been leaking on one of the seats and it ended up a moldy. He cleaned it up OK but the driver's seat didn't come out that great. I have a steam cleaner so I'll try to clean it up properly, if not I'll see if I can find a good used one. I also need to do something about the alternator whine coming through the stereo.
Overall it is a bit of a project. Given the price (a bit less than 10k for it with 146k miles on it) I think I did OK.