It's all posted at the New Yorker right now. And oh my god it's enormous.
From Alex Ross:
J. Edgar Hoover corresponds with a Communist-hunting, Philharmonic-listening Wisconsin nun; Pat Buchanan, John McLaughlin, and G. Gordon Liddy analyze Mass; and, live on tape, President Richard M. Nixon calls the composer of West Side Story a "son of a bitch." These and other highlights from the United States Government's files on Leonard Bernstein, now at the New Yorker website.
My personal favorite part is in Tape excerpt #3 in which Ehrlichman decribes Bernstein's Mass as a combination between West Side Story, Jesus Christ Superstar and Hair.
*I misremembered. In another spot, it was described as akin to West Side Story. Here it's described as combination "Jesus Christ Superstar and Hair with clothes on"