Duplicolor makes a nice engine enamel clear that comes in a rattle can, and it's only about six bucks a can. It's advertised to have superior gloss retention and protection, and it's still an enamel. I bought a few cans for the bumper I'm restoring. . .

http://www.duplicolor.com/products/engine.html

scroll down that page linked above and find DE 1636. . .I love the Duplicolor engine enamel line. ..stuff dries on like it's a powder coat. .