69 rear wheel cylinder

Hi, I am trying to rebuild the rear brake on my 69FLH. My brother owned the bike before me and he switched over to Dot 5 fluid. He had a chrome master cylinder and it looks like the chrome flaked off, fine metalic residue in master. I have a new master cylinder rebuild kit, but have found the wheel cylinder is leaking also. Can I get a rebuild kit at a NAPA dealer, instead of waiting a week for one to be shipped? Any cross reference to an automobile cylinder? The one oem part 41740-63 wheel cylinder I found on line says to only use Dot 3fluid, Should I rebuild and use Dot5 or 3? Any way to flush out5 and use 3 or will all lines and switch have to be replaced?

Works good now, flushed dot5 and re-used new dot 5. The new master cylinder was missing the spacer washer from between the piston and the clip, which was allowing the piston to come foward too much making the pedal lose prime. I had to pump the pedal once before using it every time. New spacer and all is well again.