I would at least drop the pan and clean it out...you'd be surprised what collects down there. Will give you a better idea of what you have.

OK the timing belt's been changed at 185K..but how many years has the car been sitting in the junkyard? Time is not unimportant on rubber things! A TB is cheap insurance, and you can do the front main and front cam seal too.

If it's a turbo I would check/replace the oil gallery O-rings (under the big casting that mounts the oil filter), the O-ring and gasket on the turbo return tube, and check all the rubber hoses. Heater hoses get replaced. And check the little rubber hose from the compressor to the exhaust wastegate...the 90 OEM was a pretty good piece of work compared to the 87, but consider replacing it...if it cracks you'll overboost and throw a rod.