If you do find a clutch m/cyl rebuild kit, You will find there isnt much difference in the price of the kit and a complete new cylinder.
Also check the slave cylinder for leaks, they tend to fail at the same time as the master cylinder. I would reccomend changing them both.
Al
113-042-10-014715
built 11 Jan 66
904/396 blue, Ivory Tex
condition- rust bucket