Lowell,
You can call Satish at Motorwerks Group: 1-248-668-6793. He's done a lot of work and painting on my car. They've done plenty of MB hubcaps. I think they only did one of mine however...
The place that originally did all my hubcaps was bought out, and is now Service King. 1-248-338-6000
I don't know what transpired with Service King bought the old place so I cannot speak to their current work; I do know they were certified on aluminum work etc. so they once knew what they were doing.
Honestly though, any good auto body/paint shop with a paint booth and a paint mix system should be able to help you. Where do the local Porsche, BMW and MB folks take their cars? Certainly not to MAACO. So, it's worth poking around the local car club sections (you can find all of this online) and start asking.
Have you called Automotive Restorations in Stratford? 100 Lupes Dr, Stratford, CT 06615. Phone: +1 203 377 6745