I would recommend going with a 2-part polyurethane auto paint over an epoxy primer. The epoxy primer will fill any small cracks or crazing in the original gel-coat as well as provide an excellent 'grip' for the last finish coats.
The finish coats should be overlaid with a clear coat. The final clear coat will give a deep shine as well as provide sunlight protection. It is not a good idea to go cheap on the paint as the prep work is what is really expensive, if done right. The clear coats are often quite expensive because of the amount of UV light
protectant in them. I attempted to keep the costs low by purchasing inexpensive clear coat for my Scamp
and Blazer. It is yellowing over time. :>(