[HO455]

Thank you. We'll see how it holds up. A friend told me his undercarriage painting process that he swears by.
Scrape the heavy crud off. Degrease everything. Lightly sandblast to remove rust scale but not to white metal. Wipe everything down with mineral spirts Let dry 1 hour. Put 2 coats of POR15 on 2 to 3 hours apart. The POR15 can't be sticky but needs to have drag when you pull your finger across it between coats. When the second coat has dried to the "drag on the finger" state apply the top coat. He says he has had good results with Rustoleum enamel so I that's what I used. It looks better than just rattle canning it.
I didnt do the backing plates yet as I am planning to swap the ones from the bent axle. They have all new (Well 30k miles new) brake parts.