Very cool!
I realized after seeing how easy the paint comes off the plastic why so much of the paint on mine was missing. if your lower valance isn't painted yet, I would make sure the edges of the lens insert area are bent over just enough so they don't scrape your paint off. no sharp edges to undo you efforts. I also found traces of sliver paint on that thin leading edge of the plastic lens. did you paint that edge as well? I did on mine. I'm guessing GM's process was not all that particular at the time. I would think some of the edges had paint & some didn't, but thats just a guess. Must have had some mass production mask off system & that was the transition area? Not hours of 3M making tape like us hobbyists do