>>all kinds of messages in the last groove<<
It's fun to look for this stuff. One of my favorites is on original pressings of Led Zeppelin III. In the deadwax of side 1 is "Do What Thou Wilt" and side 2 "So Mote Be It".
These are phrases from a work by Aleister Crowley who is greatly admired by Page; he has a huge collection of Crowley's manuscripts, artwork, and memorabilia.
At one time he owned one of Crowley's homes in Scotland.