I originally used a Magnetic Video VHS rip for my original bonus discs. Later, I upgraded using the CBS/Fox laserdisc rip created by Rikter. The Japanese laserdisc for this doco is just slightly better than the American one since they use the same source. Most likely, it was all shot on 16mm anyway and is really not super-high quality to begin with.

This film on eBay may have the potential of yielding something better than what already has been preserved, but it'll need to be in perfect shape and will probably still take a lot of work.

Quite a while back there was talk about using the American laserdisc rip to erase the subtitles of the Japanese laserdisc rip. I imagine it would be easier today than when it was first briefly discussed.