Re: Questions about replacign a single cylinder MC with a dual cylinder MC in an older CJ
I recently replaced my master cylinder while converting front to discs.
The late 60's CJ's had a dual reservoirs, that mounted on the frame like
yours. I too did not want to go to suspended pedals. You will need to
remove the residual pressure valve from the master cylinder, since drum
rear brakes will still need their residual pressure valve. Also, the rear brakes will then become too effective, so you will need an adjustable proportioning valve.
I used a Wagner dual master cylinder as a direct replacement for my '69 from the local Bumper-To-Bumper dealer,
# F59802. Not cheap (about $100), but a direct bolt on.
The proportioning valve came from 4WD Hardware, # 5249088 (about $50).
Hope this helps.