Cowling area rust

The cowl on my '64 Valiant convertible was rusted through when I got it. The flanges on the vents were also rusted and adding to the problem.

Since I was installing an aftermarket AC, I removed the vents, reached inside to clean the junk out...then applied rust killer and painted with rustoleum. After finishing the paint job, I covered the vent holes and rust-through with fiberglass. That was in 2001, and it's still looking good. Of course, being a convertible, it's only driven in rain when I get caught by a shower, so it doesn't get exposed to rusting conditions very often.