The SOHC has hydraulic lifters that can get varnished up and tick. Not really a significant problem, more of an annoyance. Isuzu suggested 0W30 Mobil One to clean them out and reduce the tick, but it can take a very long time to work. Others have gone with more of a drastic approach and tried running the motor with with ATF or Seafoam or whatever in the oil before changing the oil.
My SOHC doesn't tick much at all, just a little at cold start. Regular oil changes and synthetic oil are good prevention.
Looking at the ad, sounds like the guy took pretty good care of it, but even though he had the radiator "serviced" it is 20 years old. I would consider just replacing the rad...you can get a new one for less than $100 shipped...cheap insurance against another overheat and head gasket.
Make sure the tranny/t-case "service" mentioned used motor oil, not gear lube.