Hope for scratched windshield?

Many years ago a guy convinced me he could remove a deep wiper scratch and all the sparkles from the windshield of our first B'cuda. This old gentleman worked about 6 hours with diamond compound and a buffer for only 40 bucks.
The glass looked much better from the outside but from the inside.. the view was weird, wavy, distorted, kind of under water like. And the wiper blade wouldn't clear the arc about an inch wide where that scratch was either. 40 bucks wasted.