With the exterior as corroded as that... one wonders what the powder looks like inside the cases. I guess that I would just toss it, although the magazine loader and stripper device might be of use later with better ammo.
If you do clean it up, I'd avoid using Brasso as the corporate opinion is that it can weaken brass. I'm not sure of the chemistry on that, but perhaps steel wool held over a spinning case would be the best approach. Lee makes a case holder that will fit in a drill chuck for spinning the case.