Hi pghblacksmith. Welcome to stovebolt
I am presently in the process of upgrading to dual master cylinder. I am keeping my brake drums and booster.I purchase a new rebuilt drum/drum master cylinder with the same dia. bore (1.250"),and kept the same wheel cylinder.It will be under the cab and the booster will be connected to the back brakes.I had to make a bracket to accomodate the new larger master cylinder.The work should be done within the next week and I will be posting photos of the final setup. I will keep you posted