If it's not blasted clean, it will rust again eventually. If I can't do it right away, I use polycarbide wheels on an angle grinder to get nice clean metal then prime after.

68 Road Runner, 69 Belvedere, 71 Challenger Vert
340 barracuda, 01 Ram CTD, 95 Ram, 04 Ram, 85 Daytona turbo Z
66 GTO, 06 Magnum RT AWD. 07 Ram CTD, 07 Ram