As expected, the new master cylinder arrived today and I have just finished a quick test fit to make sure everything lined up. 100% success! Sadly, when I came out this morning, the shock absorber had leaked a bunch of the fluid so it looks like that part will need to be replaced.
Unfortunately I've started to catch a cold, just in time to start Autumn, so I won't be doing much on the brakes tonight, but the successful test fit has me feeling pretty good. I've also just emailed Wes at...