Michael,
When you deal with older fiberglass that has a lot of oxidation, don't be surprised to find out that the chalky faded dullness will actually begin to reappear within a few weeks and possibly even a few days. Sure you may be able to get the finish to look good, however in most cases it will not last very long before the uv rays of the sun start the oxidation process all over again.
You would be smart to walk away from any fiberglass work when the surface is aged and contains heavy oxidation. That goes for fiberglass boats and fiberglass RV's.