Bob, another vote for Bill Wzorek and a big no way vote for M&S. I sent M&S a nice set of '35 cores off one of my low mileage original cars. I got a call back from them saying my cores were all bad and were not rebuildable. They talked me into buying a set of their reproduction shocks. They were absolute junk. I only had them on my car for about 12 months before replacing them with a set rebuilt by Bill W. The M&S shocks were all leaking and loose (no resistance to movement). I asked Bill if they could be rebuilt and he said he wouldn't touch them, just throw them in the scrap pile. Apple Hydraulics might be my second choice if i couldn't get Bill to do them.
I also have some '37 shock cores if you can't come up with what you need for a set of rebuildable cores. Send me a PM if interested