Oliver Harris was alerted to this thread, read through it and found it very interesting. He wanted to add these words of reply, which he emailed to RealityStudio.org:
A quick reply to the very interesting questions posed by Paul Sempschi about Burroughs' letters. To start with, Letters 1945-1959 was always going to be a selection; what I tried to do was represent fairly the balance of correspondence -- overwhelmingly to Ginsberg and Kerouac during those years -- while including as many letters as possible to other correspondents; as I recall, I included all he wrote to Ferlinghetti, Carr, and Corso. None written to Joan appear to have survived. I say "appear" advisedly, because the state of the archives back in the late 1980s and early 90s, when I hunted for them, was not good (to put it diplomatically). Until now, the great bulk of the letters Burroughs wrote after 1959, and much of his correspondence with Gysin and many others, has been held in un-cooperative private hands.
There were indeed legal issues with volume 1, and Ginsberg made some personal requests concerning the editing of letters, but in the end no blue-pencilling took place (only a few small editorial deletions, for a number of minor reasons). Burroughs himself did not intervene in any way. The only real gap in volume 1 that wasn't necessary -- and which I now regret -- concerns some good letters in the Letters to Ginsberg, 1953-1957 volume. But at the time I was worried about being too inclusive -- it was suggested to me, for example, that I incorporate the "In Search of Yage" letters, and some material published in the Interzone collection -- and I felt it was more important to present a volume that was substantial but also highly readable, rather than exhaustive and exhausting (and messy: the "Yage" letters would have confused irredeemably the already awkward distinction between "real" and literary letters). One day -- don't hold your breath, but I am becoming more optimistic -- a complete edition will be possible, and I'd love to do it. Ditto just Volume 2, 1959-1974, which would be an entirely different book -- a much wider cultural and personal range of correspondents, but also less vibrant, more businesslike. The '50s was a special time for Burroughs‚ letter-writing; never again was it so integral to his life and to his development as a writer.
Finally, there's more of the story of Burroughs' letters soon to come in the new edition of The Yage Letters -- due out in June.
I hope this helps advance the discussion a little more; and keep going, it's really interesting.
Let's all offer our thanks once again to Dr Harris. He's a real Johnson!