Keep the old skin, it can be used as a template for a new one. If you can't find somebody in the US to make you a new one, you order a new skin from Pouch in Germany. Or you can ask Ralph Hoehn,
http://www.pouchboats.com/ although I never got a reply from him when I used the forms on his website or his email address.
If you have a RZ 85 (most likely), you can even order a new hull online at
http://www.poucher-boote.de. A new skin in PVC would cost 535 euros without tax, which is pretty cheap for a new hull. Don't get red, it seems to fade very quickly. Shipping cost is quite reasonable, I looked into it once (DHL).
You might be interested to hear that Marian Gunkel says on his Pouch boat pages (
http://www.pouch-inoffiziell.de ) that the quality of the boats has decreased between the 1960s and 1989. So your kayak is probably higher quality than a newer boat from the 70s or 80s. Many people in the German forum faltboot.de think that the RZ 85 is one of the best designs for a double, except for the assembly. Some even think that it is the best double of all, but some East German pride might be involved there...