to
clubuk matey.
Good luck finding yourself a good'un just look out for rust, unless you like welding
look everywhere and look again and don't be afraid to have a bit of a poke around, it'll save you a lot of time and money on repairs in the long run.
Also I'd take a jack with you and jack up each wheel to check for play in the wheel or kingpin bearings and give the wheels a spin to check for noisy wheelbearings and/or binding brakes.
Get underneath and check all the prop UJs and diff pinion bearings and transrerbox outputs for excess play.
Also look out for smoke from the exhaust at high revs and on start up, blue smoke could indicate that the valve stem oil seals need replacing or that it has worn piston rings. I would be suspicious if the previous owner has already warmed the engine up before you got there.
There's lots of good ones out there still, you've just gotta be patient.
If you're buying one that's already modified then give it an even more thorough look over and make sure you give it a test drive.
There should be very minimal vibrations and/or wobbles depending on the tyre size and how high it is. Large tyres do effect the handling and make them a bit more 'fun' to drive
There should be minimal bump/roll steer. Be extra careful when buying an SJ with a spring over axle conversion (spoa) check that the welds on the perches look good, that the steering isn't bodged (cut and welded arms etc.) And the diff pinions (output) should not be pointed up towards the transferbox. They are very slightly tilted up as standard but only a few degrees; not like this
Hope that helps.