I tried the more advanced timing and the below was my experience.
Result of me advancing the timing to 28 degrees
My Results timing advanced to 28 degrees 617.952 - PeachParts Mercedes ShopForum
The info in the pics concerns the mis matched Timing Marks on the Bering Caps. It has only int 1982 (yours is an 83 so you should not have that issue unless the Fuel Injection pump was exchanged for one from 82 that matches the production code).
The other issue is that the Bearing Timing Mark in your picture, you sure that is the original Timing Mark. Is there no marks to the left of it and more to the center of the Bearing Cap>