I assume it would be PCM, yes? It never hurts to include a lossless track of the original mix. I'll listen to that and the 1997 mix to see if there are any differences besides the surround.
Supplementary audio on laserdiscs was recorded on the stereo FM analog tracks, which, while not PCM, might be a better sounding source than a lossy Dolby Digital track.
The PSE (which was in CLV as well) couldn't fit an isolated track because it had the commentary on one analog channel and the Dolby AC-3 audio on the other.