Hi, Its great to find this posting -- almost 8 years later!
I have a 1987 560 SEC (W126 body) that has little chrome 15" wheels. The chrome is peeling off and I'd also like to increase the wheel size. As I understand from your posting -- I also want to put the bigger 16" 15-slot wheels from an early '90s SL on my car. When you installed them, did you have to make any modifications to the SEC? I've read something about tie-rod interference. Did you have to use spacers? A photo of what you have on your car would be great. Thanks!