Scarebird Disc - What Master?

Ummm,.. that Mater cylinder you linked to,, is for 4 wheel drum brake,, and would require you to remove the residual pressure valve, which isn't hard,, but this master is correct for disc, and is 15/16 bore.. so it's a direct bolt on.. it's outta 73 dart with disc..

RAYBESTOS Part # MC36406 Professional Grade; Bore Size=15/16"
Front Disc brakes; Rear Drum brakes;

http://www.rockauto.com/catalog/racatalog.php?carcode=1228890&parttype=1836

hope it helps