I'm not sure what you are implying.
The motor does look new.
I'll post some motor picture below.
Something serious happened to that engine.
Maybe a gasket was replaced after an overheat and owner is calling it a head job.
Maybe head is not warped.
Maybe over heating did no other damage.
.....maybe a very different problem....
Imho, boat is way over priced with the water damage you already are aware of. Then there are the unknowns.
My experience is that owners dont get slack on just one thing.....slack on many things