Joe's right-- Rhode Island Wiring is your best bet. You can also get all the correct guage/tracer coded wire and supplies to repair or even build your own using the original as a template. When I did my restoration several years ago I was faced with either buying a new harness or repairing mine--the new ones are fairly expensive so I opted to do the repair. This required stripping all the harness vinyl covering and carefully labeling all the ends. I collected up lots of metal MB male and femal terminal parts as well as the plastic connectors from donor cars at salvage yards to use in the repairs. I also needed to correct many years of incorrectly made splices by soldering in new sections and recovering with shrink tubing. It took some planning to correctly recover with the vinyl tubing and rerouting through the car but it wasn't too difficult. After having gone through this repair, I know if I really had to, I could make up a brand new harness using the supplies that RIW offers--sorry, that is not an offer to make one!
George Des