Thanks gto.

The internet does not have any original type Mk2 master cylinders.

If you try some of the parts places selling used parts (like Readspeed in Brisbane) and buy a used clutch cylinder regardless of condition (0.75"). It can be resleeved - makes them better than new. The plastic reservoir is available new. But you will need the 0.75" internals like the piston, pushrod and spring preferably from the original cylinder. Buy an overhaul kit and it should all work.