Well heck, as long as we're going back to 1977, we might as well just take the whole print with us. ;)
About the bass . . . well, it seems to me that there are some places where the recording has low frequency hits that the '93 mix doesn't have, but the reverse is also true. It's hard to tell since most of it is at a low level and not very clear anyway, but that's my impression. There are spots where the SE's added bass that the original didn't have, too, but then they also left some out. None of the remixes used the LFE channels from the 70mm, deriving it instead from a separate sound effects master, and each time they made different choices about when it should be placed and at what level. I couldn't reproduce the original exactly even if I tried, so instead I'm still mostly just going to go with what sounds right to me. But I think I'll remove a couple small things that probably don't belong, and add a few in that I didn't have before.
Thinking it over again, I've changed my mind: I guess I will remove those two effects. All the 70mm changes I listed earlier are in the end battle, which is probably what they were most focused on making sound good in the time available, and as msycamore points out, the original surround effects often tend to be partially placed in the front as well (something Dolby refers to as a 2-4 punch, which can really fill out the room), while these are not. The '93 mix added other effects that only occur in the surround, so actually it probably makes the most sense to assume that they were in this group, since so many other things were being put in at the same time.
If I do this alternate track I keep talking about, then they will of course be left in. Some extra bass could find its way into that version, as well.
Samples of what I've improved over the last version? I suppose that could be arranged. Just have to think which parts would show it the most clearly. ;)
About the other two films: well, there's not really anything about the current versions that I find lacking, so it's not strictly necessary. However, I think I would like to do them as well, as the lossless LFE from the Blurays would be a worthwhile improvement, and perhaps the (few) edits could benefit from a little more work also. Something I've noticed about the '93 mix for RotJ is that the music is sometimes at a significantly lower level than in the original stereo version, so it would be nice to splice in a few more sections of that to get it back to how it was. Also, the current version is synched to the GOUT in NTSC, but the two most prominent preservation projects, Harmy's and dark_jedi's, are timed to the PAL version. The NTSC is missing two frames compared to the PAL at the scene change from Dagobah to the rebel fleet, so on both projects there is a noticeable loss of synch at the point: from then on the audio is two frames in advance of the video, which is more objectionable than if it were a delay. I would have pointed this out before, but unfortunately I'd forgotten about it. So really this should be corrected.