Hi Billy22Bob,
Kevcostner owned the Kleemann compressor beofre he does the 3.8 conversion. Also this compressor that the ability to produce more pressure. His goal was 450+ HP and 500+ Nm. At the moment the car is running at 0.9 bar with a lot more than these numbers.
The E37 is a simple swap, because it's the same M112 engine - same housing, same size ect. If you want to swap you have to make shure that the new engine has the same transmission than the actual engine has. In other words, a MT won't fit to an AT tranny, and vice versa.
You have to use the Crossfire ECU and give it a 3.7 ECU tune. A MB ECU will run you into different problems. The engine should be from production year 2003 - 2006. Don't expect too much horsepower and torque. These engines are good runners, but no power beasts.
You can see the pictures in full size if you are registered.
Regards
Markus