Well, for better or worse, my friend decided to go for it. He decided that if more than $500 needs to go into the OM616, he'll just do an OM617 swap now instead of waiting for later...
He's sending them a deposit either today or tomorrow, and should have the car at his dad's house in a couple of weeks. Soemtime after that, the two of us will go down there and try to troubleshoot it. So, until then...