ZB3 - A single cylinder master will work just fine. The reason many of us choose to change to a dual system is for safety. If you get a leak in ANY line on a single cylinder system you have no brakes at all, but on a dual system the fronts and rears are separated so that if you develop a leak you will still have one set of brakes to stop you.
It's your choise, single or double, they both will work.
George
