So, I've got zero brakes. The master was a little soft to begin with, though I went to move it the other day and the peddle goes to the floor.

I've found out its a type 2 master, however, the resovoir pipe seems to push into the top of the master, there is a nut, and i would seem to believe there is some sort of rubber under this nut to hold the pipe in place and seal it off.
I have not pulled the master as yet.

Is this rubber re usable or does anyone know what it is so i can buy new with the master?

Thanks,
Kuch

Early bus masters had a thread, but the reservoirs screwed straight in the top.
http://www2.cip1.com/ProductDetails.asp?ProductCode=VWC-211-611-011-J 
The nut and rubber sounds like some sort of conversion? You'll probably find something that can be made to fit. There's no pressure there, just has to seal. Perhaps stamp out a stack of rubber washers or something.
Good luck
Tony