My '68 and '69 Z28s had the 4-clip style when I purchased them in the '70's. at that time, the 4 clip style was the only kind I'd ever seen on original Z28s. Monte Carlos also used a 15x7 inch rallye wheel from '70 thru '77 which also had similar trim rings (looked pretty identical but were held on by the 'continuous fingers'.. I purchased a new MC in '77, and by then my Camaro trims had a few dents/scrapes around the periphery, and at one time, I *swapped* the trims between the cars (because I wanted the Camaro to look 'better'.
Before I sold the MC, I awoke, and swapped back the trims (fortunately) because by then I was becoming concerned about the 'originality' aspects of early Z28s, knowing that would be an issue as time went on.. so my wheels also have 'marks' from both styles of trim rings, and I'd bet (with the numbers of MC s sold over the years, that sort of thing happened a lot, both with original Z28s and with the thousands of 'clones'...).
PS: The '70 MC *may* have used the same 4-clip style rings, but I'm positive that by '73 or so, the MCs had the continuous finger style), but I don't know exactly when that changed.