Question on 1965 Dart GT Charger

Certainly a repair job. It is probably structurally sound, so if it looks OK, I would keep as is. The only downside might be if they didn't prime the metal well because I have heard that moisture can travel thru fiberglass. After welding a replacement floor pan in my 65 Dart GT, fiberglass doesn't sound bad. Indeed, I added a strip of fiberglass matt over my butt joints because I had many burn-thrus I couldn't fix (yes, I had a copper spoon behind it).