These laserdiscs can fetch a fair price on eBay. Maybe purchasing them and offering them up to someone who can transfer bit for bit audio would be the way to go?
Just an idea.
Here is Halloween 4 on LD ....
http://www.ebay.com/itm/HALLOWEEN-4-THE-RETURN-OF-MICHAEL-MYERS-HORROR-LASERDISC-JAPAN-RELEASE-/181660062635?pt=LH_DefaultDomain_15&hash=item2a4bc893ab
All I have are the Divimax DVD versions of 4/5 from Anchor Bay .....
http://www.dvdactive.com/reviews/dvd/halloween-4-the-return-of-michael-myers.html
http://www.dvdactive.com/reviews/dvd/halloween-5-the-revenge-of-michael-myers.html