Soooo, after discovering this thread, i thought i'd try the same with my leaky rear master cylinder.
I got the same chinese cylinder, and proceeded with the first approach as YoungEngineer shows in the OP. But i noticed that the brake wouldn't move smoothly due to the excessive sideloading, it just didn't feel good, and wouldn't push deep enough.
So today i cut the shaft shorter following Gryphon's approach, drilled a "cup" into it and using the original ball-end push-rod on the brake lever, the whole thing just moved smoothly :clap: [size=78%].[/size]
I then tried to refill and bleed the system, but for some reason this is where i failed.
I have (K75RT) ABS, and the original FAG banjo(quite fat one) coming from the ABS pump seems to fit the new MC, only with the new bolt, as others described.
To remove air from the reservoir hose, i used pliers until no bubbles come out of the reservoir.
I then used my normal bleeding procedure, without a vacuum, which always went quite fast for me. Now, though, nothing happened so i connected a vacuum, but no matter how much i pump on the brake lever and the vacuum, i can't get the brake fluid moving... the level in the reservoir never drops. Does this mean i just have an air bubble at the MC entrance?
Any tips on getting the system pressurized, why is this failing?!?
ps. Quite disappointed to discover, the ABS system passes the startup test with and unpressurized system. Apparently it just tests the brake light switch.