Hey Red,
Before I started this power brake project. I needed better brakes to stop my Cj with 35's. It also had manual brakes, so I got a master cylinder from a 1980 Cherokee, it has a larger bore, I think it is 1-1/8", compared to the smaller CJ, around 1" MC. It fit right into the firewall, bolted right in, and brake rod was perfect length for my Cj. It worked out great, stopped Pretty well with 35's. If my Wrangler power brakes set-up does not work out for me, I will switch back to the Cherokee set up.
-joe