Quoting Neil from a thread about the mono mix:
Originally posted by: Neil S. Bulk
It's probably the best mix of the movie. Everything in it just sounds so right, to the point that I start saying to myself, "This is how it should have been all along". It's the most complete sounding version of the movie, and since it's all from 1977, nothing stands out as new, the way things in the 1993, 1997 and especially that horrendous 2004 mix do. I like the 1977 and 1985 Dolby mixes but even they don't seem to be as well done as the mono track.
In answer to your other question, the 1993 laserdiscs have 2-channel Dolby Surround in PCM format.