To respond to your specific question, I have used fiberglas cloth and CA or epoxy on the inside of plastic or fiberglas cowls to reinforce the mounting area or repair cracks. But on the nose weight issue, my Score balances a little behind the "design" CG with the Enya 61CXS or ST51, with a Randy Smith tube muffler (very light) in both cases. What motor are you using that results in needing that kind of ballast? If you MUST use ballast, attach it to the firewall with bolts. I did that initially with the ST51 and then found it flew better without the ballast. I used an ounce or two, then discarded it. Try flying the model without the ballast. Check the "bench trimming" treatise by Brett Buck that is available (I think) in the PAMPA site. Balanced a little behind the suggested CG produces really snappy square corners but not excessive overshoot on the straight sides, and it grooves and glides well, not floaty on approach to landing.