I'm preparing to use epoxy resin & fiberglass cloth in a few areas on my 85 300D, for additional strength and not for primary metal replacement.

One such area is the lower front cowl which always cracks at the seams and starts to corrode. Can I apply fiberglass resin with a Good Strong Bond over a primed surface or a surface treated with something like Permatex Rust Convertor, or can I only apply it only on wirebrushed bare steel?

I know you can't put it on galvanized steel without grinding away the galvanization or the resin won't stick.