I agree that the second film is pushing red far too much. This needs to be dialed back significantly to look natural.
It seems there is some confusion about the various sound mixes, so I think I should clear it up. According to this post by disclord on the LaserDisc Database forum, the version of the Alien soundtrack heard on the THX laserdisc is not actually the 70mm mix that was used for the theatrical release. It is, in fact, an early test mix made for the Sensurround format, which contained more bass and surround usage than the final version. It was never released to the public in 1979, because 20th Century Fox didn't end up going with the Sensurround format for various reasons, opting to use Dolby Stereo instead as they had done for Star Wars. This mix was never publicly heard at all until it was put on laserdisc many years later.
This means that the text on the laserdisc advertising that is uses the 70mm version is actually mistaken. Technically it is correct, because the mix was indeed made for 70mm prints, but it is not "the" 70mm version—at least not the one that anyone who went to see the film actually heard. It had likely been sitting in an archive forgotten and unused, and whoever transferred it to home video probably didn't realize that they'd actually unearthed a rough mix, rather than the final version.
Note that since it is an early test version, this explains why it has differences in music and dialog editing than other mixes of the film.
The 70mm mix that actually ended up being presented to the public in 1979, then, would have been a 4.1 track with identical content to the 35mm stereo version. Such a track can be found on the official Bluray release, as 640 kbps AC3. The surrounds are mono and the amount of bass is somewhat less than in the test version, but it is more finalized in editing and content than its predecessor.
Taking this into consideration, for the sake of authenticity I would say that any project proclaiming to be Alien in 70mm should include both the laserdisc 5.1 and the Bluray 4.1 versions, and that they should be clearly labelled for what they are.
Editing to add: Furthermore, we can also infer from this that the 4.1 track on the Bluray of Aliens really is that film's 70mm mix, as well.