Attached is cab I purchased that had 2 master cylinders attached to the firewall. If the mounting locations were reversed it would look correct for a hydraulic clutch set up. Can a dual circuit master cylinder operate a clutch?

 

To answer what I think you are getting I would say no. A dual master cylinder for brakes would be operated by the brake pedal only. How would you change gears if you had to hammer the brake pedal every time you wanted the clutch? You would need to have the separate master cylinder and slave cylinder for the clutch. Hope this is what you were asking about.

 

I reread the post and answer number 2 would be that so long as the pressure is correct for the slave cylinder then it should work. It appears to be more of a redneck clutch setup that is a little overkill, but then again you have a spare circuit for the clutch. I have never seen a factory hydraulic clutch setup for the slick trucks '61-'66.