For 1967, the two shields on the passenger side are spotwelded and the two on the driver side are screwed. The brackets on the driver side are engine color (chevy orange).
In Member's Rides from 2 years ago, Jon Mello's survivor Mountain Green 67 Z28 had the best photos I ever saw of "Day 1 takeoffs" of these brackets, removed when the headers were installed at the dealership:
Experts tell me these should be galvanized (the new reproductions are galvanized) but if you look again at the photos above and other originals, it looks more like plating to me.
When I did my 67, I started with some originals and had them silver cad plated at a local aerospace plating place (where they did my jack mast, coil bracket, and a few other things)--I still think it looks more correct/original than galvanized, and they've held up pretty good after 3-4 years now:
Like mrrec says, good to see others taking interest in the details.