Thought I would let ya'll know some stuff I have learned while rebuilding the brakes on my recently purchased/trying to bring back to life '59 c60 viking grain truck that was last tagged 21 years ago. In working on the brakes I found a master cylinder rebuild kit for 1"1/4 bore at NAPA part number UP33 and a reman master cylinder of the same size bore is part number P21698. It fit perfectly and was about $20 bucks more than the kit. And wonder of wonders, they had one in stock and do request a core exchange.

I know I had to do some searching for parts of this size and found useful info on this site, so hoping to pay it forward for others needing this size bore on our big bolts.