Your comment about hourly rates is interesting; Kent once said we all tend to value our labor hours at ZERO. My own father taught me from early on to NEVER value our labor at ZERO. Which means this: if you build one OM616 diesel engine for yourself as a HOBBY, no harm no foul. In your mind it was a fun learning experience.

On the other hand, if you start a business rebuilding/remanufacturing OM616 diesel engines to sell to other diesel enthusiasts, your labor now has value.

It all depends upon what you want to do and are comfortable with. At this point in time, I don't know what consumer demand is for OM series diesel engines. To me, OM616, OM617 and OM606 are the KINGS.