I found the same case for my master cylinder and just bought a new one and kept the old one around in case I want to rebuild it later...which now that I think, was not the original anyway as it was replaced years before.
I did get PMB to rebuild my rear proportioning valve because it was just like the 914 Porsche valves they do regularly for $179 (a couple years ago, so probably more now). take a look at the picture on their web site and if yours looks the same then call them.
let us know who you find to do your booster and how it works out. Thats about the only thing I haven't refurbished yet and I know Ill need to. thanks,