In Australia, Vintage Wiring Harness do a nice set of replacement wiring for several versions of CMP. Looks original, but modern reliability. Cost = around $600-650AUD. At least it was when I bought mine a couple of years ago.
http://vinwire.com.au
In my case, I need to reduce length of wiring running aft, to accomodate shortened chassis length, but that won't be hard....I hope. Back then, they had limited CMP options, but now have harnesses for cab 12 and F15A as well. Worth a look.