The poor 3116 just cannot get past its......uuuhhhh......past.
If by "past" you are referring to the fact that some 3116s had "soft" blocks, there were some--it was a manufacturing defect. You can find out if the ones you are looking at were in that batch by contacting your CAT dealer. I agree with the statement that with that much time on them it is unlikely that they are bad engines. I have 3116s and they are quite healthy at 3200 hours. My only issue with them is the difficulty my mechanic had replacing injectors on the starboard engine-only re-builts are available and 2 of the 6 he purchased were bad.
There are good and bad things said about many engines. I have heard that the GM 892 model is not desirable, and that model was in several Tolly's of the 80s/early 90s vintage, but I have never owned one so that's just hearsay. I don't think CAT 3208s can be re-sleeved and that is a negative in the minds of some people but not all and some swear by them. I have had Cummins 6s with electronic injection in one of my boats and liked them.