If you’ve never seen any data linking Mellon’s policies to the ’20s boom & the Great Depression, then a good place to start is Peter Temin’s Did Monetary Forces Cause the Great Depression? More recent work by Bernanke & Stiglitz also help complement and complicate the monetarist perspective.
I am primarily a political historian, but I studied economic history as an undergraduate with a disciple of conservative libertarian Robert Higgs, and as a graduate student with Walt Rostow, a distinguished liberal economist.
I’ve appreciated your thoughtful responses to this thread.