Over the years I have clearcoated over enamels. Your best bet would be to wetsand it down with 1000 grit and a red scuff pad (if you have enough paint on it). But as mentioned above - you may have paint reactions, so try it on a small piece first. Western Select or Nason urethene clearcoats are the most forgiving in my experience. Their both a 4 -1 mix, medium soild.
But truth be told, if your going through that much prep work, I would spring for some basecoat to lay down first.
