Most of the docs are probably already gone.
I have been reading a book about Joseph McCarthy where the author was attempting to document all of the hearings and findings - and the bizarre thing was that most of the truly important records (and mind you, these were public hearings with a document index, etc.) have disappeared. This includes everything from records of hearings that should theoretically have been in the Library of Congress to things that were in newspaper morgues or academic institutions.
Many of the papers seem to have been removed in the 90s, during the Clinton era, based on the indications of when they were last seen. I guess the Dems figured that was a good time to sanitize the records and Clinton obviously was cool with that.