Well.......... if 33 working on these same cars is worth more than two cents then I'd call that a sarting point.
The shoes are 10mm from the back including the new material when new. They are never riveted on but it could be done that way. Expect half the pad life if you go that route.
Arcing the shoes is more usefull on front brakes but then you're talking 190SL's so I wouldn't get too worried here.
The rear drums are alfin and are exspensive new. The rear drums on 113's are the same as front 190SL drums so used ones are around and usually well worn. You can't re-line a brake drum. Get a different one.
As a general word of advice, take EVERYTHING you see and hear around this site with an eye of suspicion and grain of salt. A lot of what you see, read and hear is BS.
Some of it is very correct info and some of it is pulled from this site or other internet sites by those who are good at finding information but that's all.
Hey, after all, it's just information, right?
This isn't a bad place for info but it's a good as the prople who put it here. In other words, make sure when it comes to really important stuff like brakes. That might mean having to ask someone who works of this stuff or, god forbid, a '' real mechanic. ''