I am at this point right now with my '67. The fastners that hold the upper and lower molding to the grill are a special rivet that I think they listed as "hollow shaft rivets" at the hardware store. Basically, the top of the rivet is smooth and dome shaped so it looks like an umbrella. The post or shaft is hollow. There is a special tool that compressed this shaft and crimps it in place. Once you have crimped it, the compressed shaft looks like a doughnut. I hope this description makes a little sense. I had a hard time finding the rivets so you will have to go to that one hardware store that seems to have everything and you should find them. As a back up, the guy at the body shop said if I couldn't find them, they have large-head rivets that are black that they could install with a rivet gun just like any standard rivet. The difference is they won't have the "umbrella" type head on the one side.
By the way, if any restoration shops read this page, this would be a great little kit to offer that most of us could use.