There are enough sellers which have the MP-line for sale....but the MS-line is difficult to find.
I use a lot of Caddock-resistors. As i use a lot of transmitter tubes (working on the wrong side of 1000V) these Caddock MS-line resistors are simply unbeatable.
During the years i've accumulated quite some values in the MS and MM-line. If you can specify which value you need (and in which quantities)....maybe i can help ?
Included some pictures of my latest mono-amplifier (using EL82's); again with Caddock-resistors.