Would there be a market for QUALITY fiberglass parts?

With OEM parts supply dwindling. I can't see any reason why not? A fiber hood is better than no hood?
3-5 years ago there were probably lots of folks making long term project plans that decided to grab the rare stuff whenever it would pop up. They put off buying parts they "knew would be there when they were ready". We're seeing sheet metal and other parts disappear (or have a 2 year waiting list) that we just 'knew' would always be there.

If you can make the car look stock with your fiberglass parts, and they are available when steel versions are not, that alone should keep you in the overtime.