Maybe try out an old Healey master cylinder?
Well, I actually do have a brand new wilwood master cylinder sitting on the bench that was headed for the VX......but I'm trying not to cannibalize virgin parts for the sake of an old beater vehicle.

I imagine you are working with drums all the way around... any of the wheel cylinders leaking?
Yes, and I hate them with much vigor!!! The front have two cylinder each, and the rears have one each and an adjuster on the bottoms. So far I have only been able to get one drum off because they are rusted in place so bad. Again, I really hate drum brakes.

Was the K-5 in such bad shape that the Patrol just had to be better or what? It seemed fine other than no 4wd and back window.
The blazer is a decent rig, but the real clincher for me was mileage. It costs an arm and a leg just to drive it around town, not to mention taking any trips. The absence of 4WD was a PITA too. Plus, the Blazer just doesn't have any panache, spunk, or moxy, as a former VX owner you should know that