ABS system requires a lot of work. You need the plumbing and controller and pump and valvebody. Then the rear uprights and calipers are different, because ABS cars have more rear bias (larger caliper). Then you need the tone rings, sensors and wiring. And I don't know if the front uprights need to be replaced, but you will also want to add a waring light somewhere, which might require a new driver information center portion of the dash.
And I think 18" wheels are mandatory to clear the rear caliper.
This is just off the top of my head. Big, big project to retrofit, I would say it is cheaper to trade up on the car to a 2001 or 2002.