plastic paint???

I did some 66 Valiant convertible rear panels about five years ago. I used the SEM Landau black for the lower portion and wanted a little contrast with the upper smoother portion which is, as you show, a separate part. I painted the upper portion with flat black and then added real light coats of clear to get a little bit of gloss. Wasn't exactly like the factory but I thought it looked better than when I started. Hope this helps.