I think the bezels attach to the scoops with a metal capture type clip that the screws go into so they stay on tight. You'll need to buy the chrome bezels and make sure they fit the scoops since they are aftermarket parts, which can be hit or miss.

These scoops came on 70 340 Swingers and they did have both the chrome bezels and the 340 emblems. They were also available on 1971 340 demons as well.