I have seen both style bumpers on unrestored cars. This is not something I have looked at too closely, but will as the Vintage Certification Team. I just looked at three 69 examples, my 9B of 68 has the large bumpers, my 4C and 9A of 69 have the small rounded bumpers. Possibly it is build date related or just a supplier variation. I will be looking at my other cars and report back. We will be cerifying several unrestored/survivor cars at the Muscle Car and Corvette Nationals in Chicago November20&21. One of our participants is a 68 Camaro SS L78 with 11K miles that is virtually untouched, another a LS6 Chevelle with just 4K miles and several others. Come join us at the show, the website is mcacn.com or email me at vintagecert@optimum.net
Steve