"Antelope" is meaningless in Trekese.
IF TREK made an 8XX Antelope, they DIDN'T make a plain 8XX the same year.
I have a 91' 820 "Antelope" as my back up bike ($20). It's "sturdy".
I would guess your's has the 28-38-48T rings with a 12-28 Cassette?
You can put on something like a 14-32 or 13-34 Cassette.
Get skinnier street tires.
I use 26x1.50" aired up to max + 5PSI.
Keep in mind, that going to a smaller tire also gears you down a bit.
A 26x2" tire is 4% larger than a 26x1.5". Just like going from a 25T cog to a 26T. That, and the reduced weight & rolling resistance, is like adding another tooth to the cog.
DO tires first, and THEN consider your gear change.