What exists for the audio of this movie are two things: A VHS release from 1999, and a similar DVD release a few years later that has the audio encoded at 192kbps. (Sadly for me, no Laserdisc exists.)
There was an LD in Japan: http://page24.auctions.yahoo.co.jp/jp/auction/q121326072
I assume you’re working on the English dub based on your samples, though, and I’m pretty sure the JP LD doesn’t have that.
A Blu-ray was also announced by Discotek but if they just ripped the old DVD for their 2014 DVD, they probably don’t have the masters.
I’d personally use the VHS, as I’ve noticed compression artifacts in high frequencies on 192kbps AC3 when using headphones (even cheap ones). VHS Hi-Fi is pretty good quality as long as the tape is undamaged. While it has some minor faults, you can find plenty of audiophiles praising it on the internet.