That adapter will satisfy the mechanical fitment. However drum brakes require the 'rubber' return flow delay valves inside the master under the line seat. Without that valve you cannot pump up drum brakes to gain pedal if your automatic brake adjusters aren't doing their job or are absent entirely. I don't know if any 2 bolt masters have the removable seat and the machined recess for the valves on both lines. Discs don't need/use them so that side of the master might not be machined for them.