After looking at your post again I have to say Steve makes some valid points on all counts. The bow may not be worth paying a bowyer to retiller to a lower poundage and it would be a good learning tool if you want to learn about tillering a bow. As for me, I’m not thrilled about the idea of sanding fiberglass but as Steve stressed, it can be done safely with the proper breathing protection and probably should wear some latex gloves too. Good luck with whatever you decide to do.