I am glad I asked before drilling - thanks very much for your advice on how the molding should be attached. I bought these clips from very knowledgeable parts supplier and surprised to not get the correct parts.
I found this AMK kit offered through CJ Pony Parts, does this look like what I need to order?
AMK Kit F-870 ---- AMK Products Grille Molding Hardware Kit for 1968 Shelbys.
This Grille Molding Hardware Kit from AMK Products includes 52 total pieces of original style, factory correct retainers and sleeve nuts that are required to properly fasten all of the original grille moldings to the front of your 1968 Shelby.
Now you can take the guess work out of installing your 1968 Shelby's new grille moldings with this Grille Molding Hardware Kit from AMK Products. This is the most accurate and complete kit available for your 1968 Shelby.