Contact Fiberglass specialties. What he does is he orders original replacement cowls when they were new, and makes the molds from them. Then he re-makes the cowls out of fiberglass. He has cowls that he made from his molds dating back for over 30 years!
I bought one of his cowls for my discontinued Great Planes .60 Fokker DR1 and it was better than the original. My plane is about 15-20 years old. You can call him and order it from him if his website confuses you. He's a really nice guy and I think you'll enjoy doing business with him.
http://www.fiberglassspecialtiesinc.com/
Pete