If your not successful in your hunt here's what I use: visit a well stocked sewing section and look at the aluminum button covers. Choose your size; trim as needed and buff them to the finish you want. EZ-PZ
His is for the 88-98 C-1500 series. I checked Andy's Hobby Headquarters' website (where Luca Cee sells his products) and they're not available yet. However, if you check out Lex's Scale Models, he has them for $11.75 shipped
A number of the Revell 69 Camaro reissues came with stock hubcaps. I'm not sure what was in the center of the (Chevy emblem or lettering) but it's a start. Watching some of the kit reviews on YouTube will get you more specific information