Master cylinder help

Rock Auto has them..

RAYBESTOS Part # MC36406 More Info {Professional Grade; Bore Size=15/16" Number of Ports=2 Primary Outlet Size=9/16x20 Secondary Outlet Size=1/2x20}
Front Disc Brakes; Rear Drum Brakes;

http://www.rockauto.com/catalog/more...117&cc=1088760

Your push rod should be fine...

hope it helps