I recently received an '80's vintage plug and mold fiberglass kayak in good shape. I'd like to enlarge the cockpit opening and install a new coaming, seat and backrest. The original seat and coaming was a one piece affair that fit in the deck opening and was held in place with a few dabs of epoxy. The inside width of the coaming is 14" and I'd like to widen it an additional 2-1/2". Any help or suggestions fro additional sources of information would be appreciated.