The caliper is probably usable as is. (Not really good to bead blast the inside, though.)
However, if the master cylinder bore (not the reservoir) has been bead blasted or corroded it will need to be honed shiny/smooth, or replaced if too much material has been removed. Won't hurt to try it, I suppose. But, be vigilant for leaks that attack paint and electrical plastic/electrical insulators.
Cheers,