Kelsey Hayes disc brakes

Yes. That was answered (in reverse) 2 yrs ago. The only functional difference in MC's is that drum MC's long ago had a "residual valve" in the outlet ports. But, unneeded since they redesigned wheel cylinder springs to support the rubber seal w/ metal end caps (sometimes formed from wound spring wire). Assuming your wheel cylinders have been replaced or rebuilt in the 50 yrs since (most likely), you don't need residual valves. The only other difference is the larger reservoir for the fronts, but won't hurt. Don't install the prop valve until you change to front disks.