I initially tried painting the OHC with a meduim gray enamel, but hated the results, I kept getting dust or something on it that would ruin the perfectly smooth finsh I was going for. Most likely this was a result of trying to use rattle can paint vs. a spary gun (plus this was in my garage which absolutely didn't help). I decided to try some textured paint and that did the trick. The dark gray contrasts nicely with the lighter gray interior and the texture actually looks good as well.
