I ran into this same problem on my 230SL rear brakes. I had the shoes relined and even sent them the dimensioned drawing on page 42-22/1 of the BBB. They still came back too thick. I couldn't find a thickness which included the shoe flange, because it is not constant. It is tapered thicker as it gets closer to the center rib. Since it's cast, I assume that that taper is the draft angle of the casting. The lining is supposed to be 6 mm thick. Mine was about 7 mm and I had no choice but to spend several days block sanding the lining while repeatedly fitting the hub. Fortunately, every place where the hub was tight, it left a darker polished spot on the freshly sanded lining. After about three days of sanding, fitting and hand spinning the hub, I got it to fit and spin without leaving any marks on the lining.
My wife is right, as usual. Restoring a 50 year old car (even a Mercedes) is the work of a cloistered monk, the kind of person who copied and illustrated Bibles by hand a few hundred years ago.
Take a look at BBB page 42-22/1, "Replacement and Resurfacing of Brake Linings".
Tom Kizer