drum to disc brakes on a 1980 monza

That's a major job. What is the goal? They can already easily lock up and make the tires skid. Besides all the obvious differences, you'll need a different combination valve and master cylinder. It's possible the power booster may be different because disc brakes require more pedal pressure to apply them. You'll want to find the parts from a donor car to insure you have the parts designed for that specific weight distribution. It is very important to maintain the front-to-rear balance in the braking system. If you use anything other than original parts made specifically for your car, you open a huge window of liability issues, even if the other guy ran the red light and caused the crash. A good lawyer will convince a jury you were partly at fault because modifying a safety system reduced your ability to avoid the crash.