Argh Reet, I'm sorry you're in this position. And like others have said, you sound like a really responsible pet owner.
But me personally, I would never own a pit bull or any breed of dog that has a lock jaw reflex. A pit bull killed a sleeping Collie in my nan and pops street once. The Collie was asleep in its own yard and the pit bull jumped the fence and attacked it. It was a totally unprevoked attack and no-one could get the pitbull off the collie. Someone was hitting it with a metal bar to try to get it off the collie and it still didn't let go.

best of luck with your decision.