Dear George, I believe that the Expert Stylus Company may be worth contacting. I never had any old reproducer rehauled by them myself, but I know that they are able to cut diamonds to whatever customer specification for contemporary or vintage pick-ups/styli, and I'm almost sure that they also work on very old items like a model C. They do not have an official website (too much work already, methinks), but I can confirm that they reply to e-mails and phone calls. Here is an unofficial page on which their contact data can be found:
http://www.78tours.com/Expert_Stylus_Company.html
I suggest to this Sir from Belgium to be quick and avoid custom fees until the "brexit" frenzy has still not taken place. The vertical drop of the Pound will also help him to pay the bill, which is usually on the high side.