Volcker would object to being associated with "supply-side economics". Although Volker worked for the Treasury during JFK's administration, and was instrumental in designing the tax cuts passed then, he doesn't agree with the often-made equation of the JFK and Reagan programs. I believe he writes about it in his book Changing Fortunes. And it's an interesting sidelight that no Reagan economist used the term "supply-side", that was mostly a journalistic phrase promoted by some of the WSJ writers.
I'll take your word for it, but it was a heckuva coincidence then, Reagan's tax & the Treasury's interets rate cuts at the same time. I always assumed there was a connection.