65 Barracuda Front end Rebuild several questions and a couple of observations

The rust on the K looks minimal. Take it down as best you can. If any is left (not shiny) then some rusty metal primer with epoxy top coat or hammerite alone will work. Spray lighter coats for a duller finish. ps. Hammerite fumes are nasty -

Drum brake backing plates. I don't know about the missing shield. If you find one it can be riveted - I don't recall seeing 'em on my '67s 9" or later 10" fronts.

The plugs are removed for adjusting the shoes. No big deal.