Heat Box - straightening out fiberglass?

If the heater box has a crack in it, could gorilla glue fix it or should I search for a new one. It's 50 years old so I guess I shouldn't expect it to be flawless. It is a large crack, Hope to remove the dash today and check more on the box in the morning. I have the rebuild kit for it. Should you just clean these really well, or paint them.