I have a copy of the Predator laserdisc I'm planning on capturing and syncing when time permits.
Fox have used 4.0 elsewhere - Point Break and the first two Alien movies. In the Alien discussion we reasoned that 4.0 is more likely to represent a discrete channel encode of the Dolby Stereo (the 4 channels being L, R, C and S) rather than any 70mm mix, but it's hard to say with any certainty.