Master Cylinder for 4 wheel disc?

Most people prefer ~7/8"D MC bore for manual disk brakes. Most listings on rockauto give the piston size. I would only use a newer 2-bolt aluminum MC, since who needs rust and weight? For ~$35 you can get a 2 to 4 bolt adapter (search here). I just drilled 2 holes thru my brake bracket in my 64 Valiant and used a big washer to cover the hole. Many people use one from ~85 Dodge truck (search posts).