Well thats a good answer to start, but realistically.
An adapter flange, shaft extention/cog mount - that part is relatively simple.
Would the orbit timing of the cam lobes be on time however?
Not surprisingly, they share firing orders.
OM603 1-5-3-6-2-4
Cummins B5.9 1-5-3-6-2-4
This could turn into a bolt-on OM603/606 powerup, maybe a little excitement is in order?