The problem I've had with later repairs is I can never match the paint exactly, makes me crazy but it is a skill that I don't possess. Even with a solid color and a factory pack paint it didn't match. The best luck I've had is having paint color matched and mixed and don't even try to use the original mix. Of course temperature, humidity, spray technique all has an effect on it. Color matching and blending is an art in my opinion.
There's people on the studebaker forum that have used the fiberglass fenders and like them, but I don't know how long they've been using them.