Hi William - sorry I don't understand how its obvious this was riveted. When I took the bracket off, it was held by bolts. Are the reproductions held by bolts? I knew at some point the bumper had been removed from the car because several of the stainless headed bolts were loose.
Many years ago I was involved with a Camaro parts business. In addition to the demands of the business we had our own personal project cars to deal with. There were few repro parts back then; just about everything came from GMPD. Bumpers were serviced without the center bracket. We had a machine shop make up a few dozen bolts with heads that resembled the factory rivets. So I cut off more than my share of original brackets. Yours happens to look exactly as I remember.
Just my opinion for what it is worth. Not engraved in marble.
A few memories of bumpers. By the late ‘80s GMPD service bumpers were of poor quality. The nickel wasn’t polished very well; scratches and grinding scars were obvious. The plating had no brilliance at all, much like flash-chromed air cleaner lids. For some time ’69 rears were missing one bolt hole. Beware the ‘NOS’ bumper. Or any late ‘80s GMPD part.
I recall the first shipments of repros. While the quality seemed much better they were tightly encased in bubble-wrap. The wrap abraded the plating in transit. So there were bubble wrap spots all over them. I'm sure that has been resolved.
In my 40+ years of the hobby I have seen chrome plating vary widely in initial quality and long-term durability. A bud had a shop in town do the bumpers on his ’57 years ago. Not only did they do a lousy job, buffing through the chrome in a few places today they are badly pitted despite climate-controlled storage. Make sure the shop you are using is experienced in chroming large parts. And skip the show chrome.