First thoughts: a whole lot of stuff can happen to a boat made in 1955 over 67 years of use/abuse;
However much you are paying? You have no first-hand way, or credible source, to verify its condition, and no way of knowing if the current owner would recognize serious issues if he saw them.
Trailer needs repair likely means you can't drive to the boat and trailer it home.
And last from me: keep in mind that men are optimistic dreamers and imagine that somehow their choice will have only minor rehab needed and all their friends will be jealous and that the chicks will dig it.
If Pappy shows up, he may well know the pedigree of the manufacturer and have sense of current value.