Brake upgrades!!!

[Bonez305]

So we are in the middle of doing the firewall and started thinking about brake options.
I know once we get all the small areas welded and start working on the body work on the firewall I'd like to add a good master cylinder, so I have a few questions. Been looking at a kit from UPR with a strange master cylinder for $190.
G-Body Manual Brake Kit Strange Master Cylinder



1 - Anyone familiar with this Master Cylinder?
2 - Can I add a big bore unit and upgrade brakes as I go?
3 - What are the benefits of Manual Brakes, other than the space saving?