Working on both master cylinders and don’t think front is rebuildable due to lots of pitting inside bore. Rear looks looks but is there a rear master as a replacement?
It’s worth searching the forum for Master Cylinders to find posts by members on this subject.
Sometimes the corrosion is in a part of the bore where it is insignificant.
Stan had his master cylinder re-sleeved, which is an option to keep in mind.
