Rust Converter Recommendations. Aerosol for sun faded/surface rust car.

Is this just a temp fix or is the rust convertor over rust the basis for your body/paint work. Seems you mentioned the roof, etc. I can see its use inside panels, then topcoat with a good heavy enamel or epoxy primer followed by a heavy urethane/enamel. Otherwise, JUST ask any good bodyman about using it on the outside of your car to be later primed/painted????/
There are reasons why I buy projects and do them to suit me and not something someone else attempted.