The best source we have for the mono is a 16mm print. A 35mm would sound even better if one ever turns up. The mix itself is not of low quality. Ben Burtt and company spent more time on it than the stereo and 70mm even.
I must’ve been misinformed. What I’ve heard regarding the mono recreation was that Academy mono as a standard was not of the highest quality.
Still, it sounds like what we have regarding the mono is better than what we have for the 70 mm (six track, if I recall?) audio, as all I know about what we have for that is someone’s in theatre recording of it, and a recreation based on the '93 laserdisc as a starting point.