This is a topic where opinions will vary. I've researched the composites but do not have a source nearby. I use standard construction grade materials on stringers similar to original, making certain to coat them with thinned resin to increase moisture resistance and for cloth/resin to bond better. Use a high quality plywood on the transom, less likely to have voids, floors use the same ply or flooring plywood, no OSB. Absolutely do not use any treated materials(cca). The materials Glastron used lasted 30+ years with decent care, keep dry, inside storage. Again, this is just my opinion, there are many ways to restore a boat. There are dozens of restoration threads on this site, take some time to decide what is your best path forward. Good luck to you, please pist some pictures of your restoration progress.