which hyd clutch master cylinder?

I would try to use a clutch master cyl from an early 70's truck if there is enough room to mount it, that way you"ll Know the bore sizes and stroke will work with each other. Also try and find a truck to look at or a picture of where the master cyl attaches to the clutch pedal so you can measure how far down on the pedal to mount the push rod for the master cyl.