There is only one valve but the master is a step bore. Based on my research I believe the master bores are 0.94" and 1.42". I had considered changing to a straight bore master, and may still change if needed. The calipers are 75mm bore and the rear wheel cylinders are 30 mm bore. Sorry for mixing metric and english units. I believe the C30 that the rear axle came from originally had a straight 1.312" bore master but I was considering a 1.250" straight bore master.
Fibonachu, thank you for the pictures of your valve arrangement.
I am attaching some better pictures of the existing setup.
