Hey Diesel911 (and anyone else who's interested), I've got the M-B chassis book for W115 (printed June '69), and that is the prescribed method for the pneumatically governed pump on OM615. I followed that method when installing the pump in my '74 with OM616.916, which is pretty much the same setup, and it worked fine. Not sure if it's applicable to the later engines with later style IPs, but it is legit for the earlier stuff.

Rock on!