Ok, so we have a hole in the cowl on our 73. It will likely see rain at some point. Is there a really good reason we shouldn't patch it with fiberglass? since they don't make a repop replacement piece, it would be hard to find a metal replacement. It's near the heater core, and we could actually reach it now with the dash in because we have the core & glove box out. We'd rustmort the metal after cleaning it up, then coat it with something like POR 15 (eastwood's version). Thoughts? Any reason why this would be a bad idea? 'Glass is waterproof, doesn't rust and is easier to get into this spot-plus is way more available that a replacement metal piece so it seems like the way to go...