I'm no expert, but have done my share of work on fiberglass... Are you located in San Diego? Even if not, check out this website:
http://www.dmc-ca.com/
This company is a wholesaler for fiberglass and other materials, and are very knowledgeable. They are located here in La Mesa. They can point you in the right direction as far as what epoxies/ resins/ cloth weights etc for your specific application. They are open to the public and offer small enough quantities of product for individual projects. Prices are very reasonable too, as they package all their own products. If you are in another area maybe you can find a similar supplier- Beats the cheesy fiberglass kits from Home Depot, and the prices and advice are better than the overpriced marine supply stores..
Hope that helps. Otherwise, I'm sure the experts on here will chime in. Good luck