Rustoleum makes a great tub/tile product ... https://www.rustoleum.com/DigitalEncyclopedia/product-catalog/RustOleumUSA/consumer-brands/specialty/tub-and-tile-refreshing-kit preparation is key to a good job ...
Thanks for the information!
Rustoleum or Homax tub and tile paint kits.
I would talk to an automotive paint store, or look on u-tube. Maybe Home Depot or Lowes paint department would know how to paint fiberglass. You know Corvettes are fiberglass.