For everyone following along... We did it. We fit an OM617 Turbo with a coupled 711.113 into a 1978 207d. It runs and drives

Now, we had to make a LOT of modifications to the sheet metal and driveshaft and throttle linkage, and we had to rebuild the entire doghouse too. I'll get some pictures up if anyone's interested. Basically everything in front stays the same, everything in back is 6 inches towards the rear.