As John Z has pointed out the date on the tag is when the body entered production, not when the car was assembled. Z/28s were in great demand so the factories worked OT to meet it. A few years ago there was some 69 Z/28 paperwork for sale on ebay. The car was delivered exactly 7 days after the engine was built.
Our 67 Z/28 was an 06E body with an engine stamp of V0706MO.