Packrat

I got a '94 justy dl that recently tossed a alternator belt. Roommate was driving it to work when it happened. When it was taken to the nearest shop to get replaced. They found the balancer was loose. My roommate had me talk to the mechanic over the phone, he told me a chunk of the crank was missing and wasn't worth fixing. I told him do whatever he had to do to get the car home under its own power. He ended up welding the balancer to the crank. Today, after about an hour with a dye grinder removing the welds, I got the balancer off. There's no chunks missing from the crank, but the keyway is wallowed out, is it possible to fix this?