I upgraded my wheel cylinders and brake shoes to modern parts, thanks to the information found on this site, and found out the original type master cylinder could not handle the pressure.
I decided it would be better to switch to a split-system than to purchase another original type master cylinder.
I went with the A1 Cardone 10-1489 master cylinder(information provided by Binford in this topic: http://www.m715zone.com/vb/showthrea...hlight=10-1489 )
Here is the installation in pictures:
I robbed the brake lines and proportioning valve block off of this early CJ7.
The lines screwed right into the new master cylinder.
I removed a locating tab from the very bottom of the bracket and enlarged the mounting hole to match the M715.