Hank,
I had the alum rub rail on my 1970. I pulled it all off. Cleaned off the resin soak tape that was factory orig. Also cleaned out between the cap and liner with a small wire wheel. After all that I calked that joint with 3M5200 and screwed tight (through existing holes). Once it was all set up I removed the screws, filled the holes with thickened epoxy and sanded. It seemed nice and tight and was ready for my new taco rail
Some guys have put epoxy in the hull cap joint but my rivets were still good and the new rail is screwed off well. Make sure you seal your new screws going back in too.