Without a complete logbook, or without any logbook. Missing since TTSN =0?

Is there a record of registration, certificate of airworthiness?
FAA records on a CD can be ordered for about $10. That might yield some information. Hours when 337s were filed or if hours were reported as part of a bill of sale. Not always but you never know what some people may include that becomes an "official record".

All ADs would need to be reacomplishlished. If an AD said, "replace part" you'll need to find the part and replace it, because you don't know if it has been changed or not. So replace it. Are the parts still available from the manufacturer?

I would expect that any life limiting inspections and parts replacements would need to be completed. You don't know hours or years on the parts that are replaced on life extension inspections.

So I guess the question is, how much work are you prepared to do?

Bill T