Check what records are available.

Same engine an in a 300E so read up on that. The engine is easy to service but you can lose your sanity chasing rough idle and two cranks to start when warm. Someone quoted the manual in saying that two cranks to start when warm is normal. I doubt anyone would pay $50K for a new car that behaved like that. Expect to need a head gasket and valve seals, possibly valves guides if it hasn't had a valve job. Put a hedge bet on the transmission if it hasn't been rebuilt. The wiring harness should be fine.

Sixto
95 S420
87 300SDL