Sorry I can't help you with your problem old mate, I don't know a thing about pit bulls.
What I do know about however is fighting rings, and I think it is really great of you to take this dog in and give it a decent home.
In our street where I used to live in the Blue Mountains in Australia, about 5 dogs went missing from peoples homes, it was found that the stolen dogs were used as bait to enrage fighting dogs ...evidently there was one near to us that we all didn't know about. I moved from that area about a year ago, and rented my house to two policeman...before I left I told the policeman of the matter and about the rumour circulating about this dog fighting ring, enquiries in the neighbourhood were made, and to date no other dogs have been stolen. The dog fighting ring was just probably relocated.
It's just terrible that peoples pets are taken and torn to pieces, just for the amusement and betting needs of some scumbags in our community.
Best of luck with your new pet mate...I hope all goes well for her.