Drum to disc conversion questions

Hello everyone, I haven't been around for a while, but now that it's summer, I'm back to working on the 67 barracuda 440/4speed project. I bought the Scarebird conversion plates for the front and have got them installed, but I'm trying to convert it to power brakes (it was manual before),
what booster/MC do I need? In the instructions that they provided, it says they would recommend a 73-75 power dart MC, in order to convert to power brakes, is there some kind of bracket that can be used to mount the booster where it needs to be? or do I just cut off the studs that the MC mounted to and drill holes to accomodate the booster?
I have an adjustable proportioning valve so I don't need a fixed one that will 'match' the setup, which leads me to my next question:
what exactly is this? I know it's a brake light switch, but is it also a propotioning valve or something? there's another a foot back on the rear line, but it's just a single in/out, is that a valve or just a smaller hole to restrict flow to the rears? do I need to leave these in? or take them off when I put the adjustable proportioning valve in?
Thanks in advance guys, I searched around on here for an hour but could find what I was looking for in previous threads....thanks guys :)