A car with the OM617 in a W123 is still pretty common. I think it would be cheaper to just get one at the yards.

OR, are you doing a manual conversion. If you are doing a manual conversion, please let me know. I can post pictures of the front driveshaft section, with measurements, which goes to a five speed Getrag 717.400 mated with a OM617. I also have the front drive shaft section which goes to the OM616 mated with the Getrag 717.400.

I do not have the front drive shaft section for the gassers, e.g., M110, however.