Try pgauto.com (Potomac German Auto) They're a quality salvage biz that handles MB only. (Ask for Pat, he has a 190E
and is very knowledgable about these cars.)
Also check out this forum if you haven't already:
http://azure.bbboy.net/190revolution. Lots of good folks there with lost of good information. Plus there's a classified section that might have some of what you're looking for.
Good luck,
Jeff Pierce