I delt with it on a '70E. The metal was all in good shape but there was some surface rust. What I did (fenders removed):

- Clean thoroughly. Vacuum, compressed air and a pressure washer. I repeated until I was sure all leaves, dirt ect. were completly removed.
- When dry, I sanded and wire brushed everything I could reach and cleaned again with vacuum and compressed air
- I used a rustproof gun to apply primer. This is the gun with a flexible wand and a nozzle that shoots out in all directions. I used Eastwood Rust Encapsulator. This is messy but it coated all the hiden spots, seams ect.
- When the primer was dry, I painted the same way with Rustleum aluminum paint.
- Actual painting of the car was last. Visible areas under the cowl vents got a coat of body color.

This worked out well. For the primer I would recommend the Eastwood Rust Encapsulator, Rust Bullet or Red Rustoleum. These work well with light prep. POR 15 requires perfect prep which is hard to do in the Cowl area.

A final step could be application of waxy rust proof with the rust proof gun (Eastwood or similar). I didn't want that mess before painting the car and figured the two coats of paint would be sufficient for a 3 season car.