We use a lot of fiberglass on our track cars. The fit and finish is not critical for us. If it was, boy, you would have a lot of work ahead of you. Our '65 coup runs a glass front end as does our '66. I can pick up the hood with one finger, very light.
They look great going down the track at 100+ but sitting still, they don't. I have seen glass made to look nice but I'm not going down that road. I have done body work and I would say it would take 2-3 days worth of work for each fender. A lot of glass would have to be cut out and replaced and some "open spots" would need filling in.