The results are in!
Paint may be an entirely different issue but epoxy primer cannot be removed from powder coating without ruining the coating. Lacquer thinner,acetone, carb cleaner, diesel fuel, gasoline, TSP, do not work. I have tried them all with no success, I ended up having to lightly scuff the PC then fog it over with top coat and then clear.
67 RS/SS 350, M21, 3:70 POSI, Hooker side mount headers, blue dot tail lights. owner since 1974.