Actually, scotch bright is what I would use on the pits, I keep a red/maroon scotch bright wheel on my grinder, I think it is only 1600 rpm. When removing semi deep pits, really any pit, use and X motion and go lightly, whether with a power tool or my hand, it is less likely to show a flat spot as it blends into the good metal around the pit. I keep a separate grinder motor fitted with a 6" felt wheel, for polishing with different compounds. That action would also look great with a bead blast finish, followed by phosphate or cold blue finish.
A word of warning, glass beads and most blasting media, gets into everything, and can be very difficult to remove. I use modeling clay to plug holes both great and small, especially that big ejection port. I keep various sized natural cork and rubber cone shaped plugs, to plug muzzles and chambers, both to keep things out, and to keep things like bore solvent in, where you might fill the barrel up completely for a badly neglected/fouled barrel.
Keep going TW, I'm sure it is going to look great.