And it looks like a Chevy bell housing can be had giving you large diameter / easier adapter manufacture. Plus access to off the shelf Chevy flywheels ( maybe redrill to Mercedes ) / clutches.

In the performance section, look at what I posted for OM606 to Chevy adapters, it might be of some help. http://www.peachparts.com/shopforum/performance-paddock/351545-trans-adaptors-om-60x-should-fit-m103-104-a.html