After 4 years of secretly restoring my mother's car. I surprised her with it!

This is just awesome! I'm very sorry for the loss of your Dad. He must have been a great man to have set the examples that you follow without even realizing you are doing it. Not sure if you want more modern seat belts for her car, but here's a link to a place that has nice belts at affordable prices.
Seat Belts Made In USA. Styles And Colors For Most Makes.Call:(302) 629-8508