I am using a AR adapted late model 1.03 alloy master cylinder unit at this time , no booster,on a manual drum brake pedal the car was made with .A Baer tech said to use a 15/16 or 1" master ,so I might need to change it after the front swap but I'm going to try the one mounted on the car now.The pedal effort went down with the rear disk swap and its a fairly small piston caliper at 38mm,or 1.5",so perhaps the large rotors, high friction ceramic pads, braided flex lines and stiff alloy calipers that came from Baer will compensate for the smaller piston size .I'll soon find out and post.