Bob,
First, Hello to a fellow Pittsburgher! I was born and raised there but now live in York PA. As you can see by the pictures in my signature I have 3 older vehicles that I take care of. The Morris is a clear coat so it doesnt apply here. The 52 Chevy is the original paint and was (and to some extent still is) very imperfect. however, after polishing I did use Paint Sealant and H2O G&G and it is much better than I expected. The MGB was repainted about 25 years ago( I was told) but it is a single stage. After polishing, I used paint sealant and have used Americana over the top. I love the shine that gives. Mind you, all 3 cars are garage kept but, they are driven as much as possible (at least once a week each). They just dont see a lot of bad weather unless it rains while i am at a show or cruise (which has happened a lot more than I would have liked). Good luck and post some pics of the Catalina (my first car was a 67 Grand Prix convertible)