OK, I finally downloaded these and listened to them. Apparently, these are not the *original* mono mixes, they were restorations/reconstructions done by Paul Rutan.

They sound to be in some sort of rechanneled "duophonic" simulated stereo, and most of the songs still come from higher-fidelity sources than the dialogue scenes, but at least they utilized the mono mixes of the songs, instead of dropping in the stereo album mixes like the MPI versions.

I would still like to hear the true original mono mixes someday. Anybody got any recordings of old TV airings from the late 70s/early 80s?