Yeah, I’m definitely going to redo the other two movies using the same methods.
For receiver settings, I suspect that letting it play in standard 5.1 mode is best. The Shure has already added its own processing to the surround channels, so compounding this with additional processing in a receiver may yield a result that doesn’t sound that great. I can’t fully comment on this, since my system is 5.1 and I don’t know what this mix would sound like in 7.1 or Atmos firsthand, but I can’t imagine it would fit very well with what the 5.1 is already doing.
If you absolutely must upmix it further, try Prologic IIx in music mode, rather than movie mode. This should spread the surround channels out among the speakers rather than trying to specifically pan things like movie will do.
That tractor beam bass was always one of my favorites. It is essentially a sine wave starting at around 60 Hz, passing through an LFO (low frequency oscillator) and being varied in pitch and speed as the ship struggles to escape. This sound can clearly be heard on the in-theater 70mm recording, although it distorts because the microphone on the tape recorder was overdriven. Only the 1993 mix contained the correct version of this sound; the special edition mixes have versions of it, but they’re not nearly as good. In previous versions of this soundtrack I tried to boost what was in the '93 source by adding a copy of it to the LFE channel, letting it play along with what was already in the main channels. Unfortunately, bass management settings in receivers can cause correlated signals like this to become out of phase, even if they are in phase in the mix itself, causing this kind of duplicated bass to cancel itself out rather than get louder. I’ve heard it played correctly on some systems and completely wrong on others for this reason. The solution ended up being to use the '85 mix for the main channels here, and putting the low-pass filtered '93 bass separately into the LFE, so that there is no correlation between them. This way there will be no possibility of cancellation regardless of what the playback system is doing.