we use to use humbrol enamel for painting 2 stroke exhausts to protect them from road salt it would smell till it cured but was resiliant enough for the job at hand
I use Paragon paints which are the type of paints that would have been used on Traction engines etc. Good stuff and their UV clear makes the paint shine!
I didn't like the 'Olive / Brunswick green that Stuarts provided for my engines so, to paraphrase what Maurice said 'use whatever you like, I did, still on the green theme…