Before you make decisions, check out the laws in your state. When we lived in OH my daughter was bitten by a dog. The horrible woman who owned him "rescued" him from a friend who was going to put him down because he was aggressive. She was NOT part of a rescue group, just trying to be better than the other lady. She had NO training for him, and it was bad. The laws in OH stated that if you give away or pass along an animal that had been aggressive YOU are liable for anything the animal does from that point on. We had a cat that started biting. Couldn't place him, even through SPCA because we would be liable if he bit someone. That was a risk we could not take.
So check your laws, decide what you can do. But if you keep him, he has to KNOW youare incharge. Not sure how to do it, but a trainer will help.
Hugs,
Susie