I can confirm the use of flat black Automotive primer as the preferred paint for badges and motor tags. I have found that the best clear lacquer is Eastwood Diamond Clear which won't cause the nasty orange peel and will darken up the flat black to a deep black. It wasn't available for a long time due to issues with the EPA about one of its components. The company must have reached an agreement with the regulator because it is available now. Good stuff!
This is a good automotive primer.
Here is Eastwood clear gloss.