The Network and All the President's Men blu-rays feature the original mono mixes.

I just played catch-up on this thread--best discussion ever!--and just want to add that I've always found directionality, be it 2-ch or multi-, to be far more distracting than immersive. Plus those old '60s albums sound so thin and empty in the "stereo" versions.

"Stereo" is of course the most abused misnomer in audio, when really it's all just 2-channel, except for a very obscure group of genuinely stereophonic curiosities.

As for multi-channel, that shit is just more cargo! What a waste of money and space!