1967 Z28 engines never received the finned balancer. My company, CHP has rebuild dozens of original '67 302 engines, judged at the Camaro Nationals many restored and original '67 Z28's and never has one turned up on an original engine. They were used in 1966 and have been seen on the '66 L79 engines.
Have been running the national registry on these cars now for 30 years. Yep, since 1988 and all of my data shows it was never used. I hope this helps.
Jerry