I have been changing all of my cars over to manual brakes. After running my '74 Duster as is with the factory manual disks and master I decided it was far better than the power set up for brake feel and modulation, and not that much worse for actual brake effort. Worth the trade off. I've run my Duster with the stock master and stock disks, the stock master and 11.75" disks, and currently run it with Dr. Diff's 15/16" aluminum master cylinder and his 13" cobra style disks with 11x2.5" drums in the back. That set up works great.
I also recently changed my Challenger over from power disks to manual. It had the stock power master cylinder with 11.75" disks and the 2.75" calipers. I switched it over to Dr. Diff's 15/16" aluminum m/c like the Duster. The 15/16" m/c moves more than enough fluid, the pedal is impossible to hit the floor with. It does have a little more travel than a 1-1/32" m/c, but I find that gives a lot more ability to modulate the brakes and it reduces the amount of "leg" needed a little. Not much, the feel and modulation factor is why I run the 15/16" not the force needed on the pedal. I also run 11x2.5" drums on the back of the Challenger.
Dr. Diff also machines the back of the m/c piston to work with the manual push rods. It's probably not 100% necessary, but it keeps everything working as it was intended. The only beef I have with his m/c's, and it's not his fault, is the gaskets that come with the m/c from the factory. By the time you're done bleeding the brakes they'll start leaking, I think they only last for one or two tightening cycles on the caps. I just replace them with Dorman caps and gaskets, those work fine.
