Thanks for the quick response, Ryan.
If I understand your suggestion you would have me just place the Prusa extruder on the MP3DP??
The vertical distance between the X Rails are not the same.
I believe I would need to modify your X gantry, to receive the extruder body of the Prusa I3 MK3.
Additionally does Marilyn have native support for the z probe and the filament sensor??