jim8flog
Journeyman Pro
IIRC, the previous drop was over your shoulder, not over your head. Further, here's what it says in the 1968 Rule book, "A ball to be dropped under the Rues or Local Rules shall be dropped by the player himself. He shall face the hole, stand erect, and drop the ball behind him over his shoulder." "Head" is not mentioned, other than facing the hole.
If tried to drop a ball over my shoulder (behind me) directly it would strike my body hence my comment about needing to be a contortionist for it to be shoulder height (the requirement in the later revised rule) (remember it was still the rule ((as far as my memory serves)) that if it struck your body it must be re dropped).