Been having issues getting the brakes anywhere near so gave up with messing with the new (but different) brake master. Even the p/n on the original microfiches lead to this cylinder but its not the same. I took it off and looked to see if I could use the guts in the original cylinder.
Nope
So while I spend months or years trying to source the right cylinder I decided to clean the old one up as best I could and use that for now. It actually came up really well with various abrasives and cleaners, all the rubber looked very good considering. The difficult bit was the inside of the cylinder being so deep, eventually I cobbled together a 10", 1/2" drive extension, with numberplate tape stuck to it and fine grade wet & dry paper stuck to that. I gave that a razz around the inside of the m/c and it came up great!
Bunged it back on and realised this is 4 x M10 ports, the other was 2 x M10 and 2 x M12, so I had to cut the flares off and reflare 2 pipes on the car, pain in the arse!
Got it done, and in, did a bunch of pressure bleeding, and I now have a brake pedal

(the zip ties are to stop the push fit feeder pipes popping out with ~30psi from the pressure bleeder in the system, usually this is just gravity feed)
Short update, yes, but it means I have a usable handbrake and footbrake now, thats a significant step forward in major systems.