Dave - you are correct with what they did wrong with stupid stuff like drilling and screwing without properly isolating. It was common practice on many boats built in that era. Just think if the boat builders took the extra minutes to overdrill, fill and epoxy isolate. Never mind the really dumb stuff like isolating the exhaust tube with 5200 so it could shrink and expand as it heated and cooled....

I've seen a couple J/109s that have had significant hull core work done after failing pre-purchase surveys so the boats could be sold because aftermarket stuff was installed with cables run through the bilge that were neatened up by drilling screws to mount zip tie cable clamps.