If you think about it, the W109 had the M100 6.3. Power was a bit more raw back then.

With-in a week, I've made some decent progress testing with the W210.

If you unplug the ABS Pump (dyno mode)
Yaw and tilt sensor
Steering angle sensor
Both front ABS sensors

The engine and trans will not go into limp and the engine will perform as expected. Based on this, I can run the ESP module with 1-2 rear ABS tone rings to help the trans understand wheel speed sensor and successfully run my swap. I'm going to keep disconnecting pins on the ESP module till it goes into limp mode for simplicity in my wiring.

Engine: ML500 M113 5.0
Trans: CLK430 (Trans control E430)
Rear end, W126 early w/ 2.83 gears (Need to look at SDS and ensure gearing will work)

I'll make another video of the motor running on my stand to prove its possible on a budget

Here is my original while coding my new keys to the EZS/ESL/ME
https://www.youtube.com/watch?v=DBNj1m23Hs0