I have the entire 4-wheel disc kit (with that booster and master) from the same eBay vendor on my '68.
I have no complaints with mine, the install really seemed to go smoothly and the quality was better than I expected for the price I paid. I don't have very many miles on the set-up at this point, but it has been trouble free so far! You'll probably want to paint the master cylinder and proportioning valve bracket before installation.......the master will start getting surface rust quickly if you don't.
The installation is on page 5&6 of my build thread.....I had to find an adapter for the proportioning valve output but that part number is in the thread too if you need it.
Please ignore the ugly firewall......I hope to get that MUCH better looking when the engine swap (finally) happens.
I hope that helps.