Not sure if this is what you're looking for, but the easiest thing might be to go all the way back to VHS. As you rightly say (and to lift from Wikipedia) there are many versions of the film:
The video was a hit in the United States...Highlander was first released to DVD in the United States in 1997, in a "10th Anniversary Edition" Director's Cut that contained the
international uncut version of the film. A "15th Anniversary"
edition was released in Australia in 2001, which also contained the
International cut of the film.
Highlander was again released in 2002 in two editions: a special
"Immortal Edition" with several extra features (including several
Queen music videos and a bonus CD containing three Queen songs from
the film) and a standard edition, both of which contain the
International uncut version. On the June 17, 2009 French
distributor StudioCanal issued the film on Blu-ray with identical
releases following in Germany, UK, Holland, Australia and
Japan. The U.S. director's cut is currently available on DVD in
North America from Lionsgate under license from the film's current
owner, StudioCanal. 20th Century Fox, the theatrical distributor,
remains the television rights holder.
So, certainly a lot of different releases!
Now, whilst you mention wanting the original soundtrack, it sounds from your question that you're really after the original audio.
Part of the problem here is that, whilst some reviews criticise the audio, the majority of them for the DVDs and Blu-rays talk about it being very good (or at least as good as something uplifted from a 1986 movie can be). I found the review you point to on Amazon (discussing the 10th Anniversary Edition) but I found similar reviews for the 15th Anniversary, the Immortal and standard 2002 editions, and the new Blu-Rays.
Therefore, I'd suggest checking out the original VHS release from the UK and seeing if that satisfies you. Failing that, the Blu-Rays have gotten the most positive discussion otherwise.
I do believe that, ultimately, some consideration needs to be given to the fact the film is from 1986 and, like many films from that era, doesn't have audio anywhere near the standards we expect in this day and age. I'd strongly argue many of the reviews I read haven't accounted for this fact.