I'm no engine builder but I have a freind that has a PF 532CI BBC that was built in 1996. It makes 850HP and this thing has been pretty much turnkey ever since he got it. He runs the blower at about 10 under and changes the oil when needed. This thing still runs perfect and looks perfect. I don't know how many hours it has but I would guess about 100 or so. Not bad if I do say.
I have a twin turbo I rebuilt a year and a half ago. It has about 700HP and time will tell how it lasts. The motor before the rebuild was about 20 year old.