Few spray bomb paints will be as durable as something that has a hardener in it. You can have a paint supply store mix up catalyzed paint. It has a pin in it that punctures a bubble in the can to release the hardener. You have to spray ALL of it in a short time though or the paint dries in the can.
On the other end....Mopar Action magazine did a bit on a guy with a 67 Coronet...THey liked Rustoleum but said it dried SLOW. The only problem I see with that is bugs or dirt landing in it while waiting for it to dry.