I just grep'd for Prouty and nothing showed up. Even his wikipedia page [1] is a bit scrubbed and buries his important act of blowing the whistle on the shadow government [2]. Btw, Prouty discusses Ellsberg directly in his book. It is 'interesting' reading for sure.
Prouty was certainly a very interesting fellow, but unfortunately his best-known "revelation" -- regarding the role of the so-called Secret Team cabal in the JFK assassination -- appears to have been basically a morass of unfounded speculation.†
And of course, his later dealings with the Liberty Lobby and the IHR didn't exactly help to burnish his image much, either.
† Unless one buys the Secret Team / JFK hypothesis, that is -- which I don't.
[1]: https://en.wikipedia.org/wiki/L._Fletcher_Prouty
[2]: https://en.wikipedia.org/wiki/The_Secret_Team