Master cylinders

Perfect. I'll remember the rear disc swap if/when I come to it.

The little.rubber seal that is mentioned in that pushrod removal post, is that included with the MC36406 type MC? or do I need to purchase one myself?

If so what is it called or where can I find one?

Should come with the new M/C .
If not, a small piece (as picture) of vacuum, rad overflow hose or similar will work. .