I'm a fan of the film. Barry's score is one of the best things about it. I used to rent the old Disney Laserdisc often because the only store that had a copy wouldn't sell it to me! ;)
The overture was legitimately released in the 90's on a compilation CD of Sci-Fi movies scores put out by the SciFi Channel. It has always sounded great to me.
It's also present on the old Anchor Bay DVD (in 5.1) and the letterboxed VHS boxset. (Did Disney include it on their DVD version?)
A friend gave me MP3's of the vinyl and the Mask CD. The mask version sounds very good. There is also a disco version of the soundtrack done by none other than MECO!