You should be able to find standard loaded .38 Super at the bigger gun shops. The big retailers (Bass Pros,Cabelasand Gander) probably won't have it.

The .38 Super was never a very popular round, most people figured if you were going to carry a full sized autoloader it may as well be a .45
However, ballistically it is a decent enough load. I shot one years ago for awhile before the 9mm became popular.

Good luck, and enjoy your Dad's pistol.

Good Hunting,
Bowflex