the MC size should correlate to calipers you are running.
The prop valve isn't really that important and with a setup like this (the pedal assembly you posted) you wouldn't even use one.
You would run one like from resivor A to the front calipers (T-ing the line) and from resivor B you would run one line to the rear calipers again T-ing the line.
You can install a bais valve with out the addition of these pedal though.
The bigger question/ what should be answered first is..
Why do you need this setup? What problem are you trying to solve?
The prop valve isn't really that important and with a setup like this (the pedal assembly you posted) you wouldn't even use one.
You would run one like from resivor A to the front calipers (T-ing the line) and from resivor B you would run one line to the rear calipers again T-ing the line.
You can install a bais valve with out the addition of these pedal though.
The bigger question/ what should be answered first is..
Why do you need this setup? What problem are you trying to solve?