Those master cylinders are very hard to find, and they would be NOS. The take-offs almost always have just enough pitting/corrosion that they will have to be re=sleeved. Soft parts are available, but don't take a chance on putting them in an imperfect bore - and don't hone them so much that the soft parts lose their proper fit. The brakes on these trucks are challenging, but if you get them right, they will last a very long time.
