Hi Mate,
Try these guys.
http://www.apvsafetyproducts.com/index.htmI went into REPCO to see if i could get belts for my 1200 coupe and was told to call this company. This company supplies REPCO with their aftermarket belts. They do non-retractable ones. just give them the lengths you need for belts and buckles and happy days.
Also if anyone has stock belts in their coupe it would be awesome to get measurements for the belt sash and buckle. Just saying :)