Dave,
The top is made of fiberglass, and after a few years the sun has a
tendancy to dry ot the fiberglass resins, and gel coat.
My suggestion is to sand down the top with no less than 180 dry paper,
prime with a high fill primer, (Sherwin Williams ultra fill is real
good) and sand again with no less than 360 dry paper.
I like, and have used for at least 15 years, PPG Deltron ( modified
acrylic enamel urethane ) It drys fast, and is very durable.
I have been using it on Mack Trucks, and especially the hoods, being
fiberglass, seem to hold up very well with a minium of maintenence.

Good Luck,

Terry

85 GL