1987 Pontiac 6000 STE 2.8 electronic motor and pump

1987 Pontiac 6000 STE 2.8 mileage: 100,000. My car has wheel disc brakes with ABS. The braking system has an electronic motor and pump. The motor and pump must be replaced. New it is over $1,800.00, used, or rebuilt cannot be found. I have been told that this system was only used for a year or two. My Question is: Can I install a regular braking system from another Pontiac 6000, without ABS? How hard would it be? Would the cars computer system need changes?