Thanks for the response. I'm hoping that the seller was naive enough to not know he had a broken head stud--but his "story" did not make sense to me.
Missing stud/nut was in the second row from the front (looking at carbs on left) on the carb/intake side.
Is it possible for the stud to break without any loss of power and without an immediate head gasket failure? Engine idled smooth. Only witnessed it running inside of his trailer.