Master cylinders

Your current brake lines will screw directly into the new M/C, no fittings nec.
Pushrod will be correct .
The residual valve can be removed by screwing a self tapping screw into the metal "seat" of the small chamber reservoir outlet, and pulling out with plier, vice-grip, or similar.
Remove the rubber "joker/residual valve and spring".
Reinstall the metal "seat", secure by installing tube, bleed as nec.
The K/H calipers respond very well with this M/C.
I have, and will continue to use this M/C in all my conversions for it's absolute simplicity, and to maintain stock appearance .

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?