Need help with master cylinder

For 1970 with k-H fixed calipers, 10.75 rear drums, Chrysler p/n 2808 600, casting will be 2225541
You may be able to still buy a replacement (old stock) from Kanter. Look ebay with the part number and then the casting number if that fails. IIRC the username there is oldcarparts.
For 1971-2, the m/c was 9461178, casting 3461187.
Work in progress cheat sheet here:
How come all my manual drum cars have disc master cylinders?