I would not want to own a pit but my neighbor has a pit and she is very good to my Yorkies. She is large and I am always afraid of her trampling them down when we bump into eachother but so far (2 years) so good!
I would say, make a deal with your hubby, get the yorkie first...for a few months until your yorkie is 5-6 months old and sound. You can justify this to him by the size of your Yorkie compared to the size of the pit puppy...Once your Yorkie reaches that age, introduce the pit as a small puppy. Make sure to do your research on the breeder. Who knows, by the time the Yorkie is old enough to have with another (large breed) puppy, your husband might not want the pit anymore...