Okay I know this sounds crazy but I believe I have this 78 I found coin roll hunting a while back came across it you're recently and it has every feature that the 1964 SMS accented hair Kennedy half dollar has which includes the no serif on the letter i of liberty as well as the broken raise on the back of the coin where the stars are at and the black carbon marks on the front and back of the coin as well as of course the hair.
There can be no correlation between some features on a 1964 coin and one struck 14 years later. Those are just die markers to ID a specific die, which obviously was not used to strike a coin with a different date. Any small anomaly on a die can also happen at different times, coincidence.