The two engines used very different engine management systems. We did that install on a car years ago and had no problems (actually it was a 500 into a 380). I am pretty sure we used all the 380SL management system.
What kind of fuel dist is it? Is it a KE with EHA or a K-jetw/Lambda using a frequency valve?
I think you would be best suited to finish the system that is working with the fuel dist as the controllers have to work together.
Bosch Master, ASE Master, L1
33 years MB technician