GDA,
I can understand why you would want to "get this right" the first time, but I'm not immediately aware of the proper mounting specification ... and, being a product of German engineering, you can be certain that they do have a prescribed method of doing this, down to the millimeter.
Part of the problem with badging a Euro M5 is that you almost never see a badged M car in Europe ... at least not here in Germany. I've looked at more than a dozen E34 M5s (including my own) here in the Fatherland, and not one wore the factory emblems. Most were ordered that way from the factory, as the Germans have a real thing for understatement ... they call such cars "Tiefstaplers."
I would go back and study detail photos in the member registries at both
www.bmwe34m5.com and
www.bmwmregistry.com to get a visual concensus on positioning.
Chuck