Um, surely the hours would be in the log-book associated with the particular engine.
In the absence of any paper-trail, one would make the huge assumption that this would see the engine treated as a "worst case scenario" which would meana full strip and rebuild by suitably qualified person(s) in suitably approved premises,
Note I have sidestepped Lomapaseo's specifics
A single-seat microlight "Robin" engine may well be a candidate for a strip in your garden-shed with your Halfrauds budget "500 piece mechanic's toolkit for £15 "
On the other hand, a Continentalwhich could have had a prop-strike with serious shock-loading, would need a somewhat more professional and rigorous approach.
I make the assumption that you haven't aquired a couple of cheap Trents suffering slight dirt and mud ingestion
There again, I may be spouting verbal diarrhoea.