Buying a Catalina C320
I doubt that you would have much to worry about unless there were problems in the hull layup at the time of manufacture. But crazier things than that have happened, so I would have the most "suspicious" survey I could obtain. And who applied that barrier coating--Catalina, the owner, and what did they use? Never assume anything. Just as important is being assured that there hasn''t been any hull damage. But I doubt you will have much trouble.
PS. How did you obtain the surveyor? Assume he isn''t the recomendation of the broker, if there is one.