We usually rebuilt master cylinders "in place" by removing one or both end caps and replacing the pistons and seals. If the area of the cylinder where the piston travels isn't rust pitted, there's really no reason to remove it from the frame. I've even honed a few of them "in place", although cleanup of the abrasive residue from the hone can be a challenge.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!