*sighs*
That dog is a quarter Pit Bull and you are worried about it? What you are going to adopted is a Mutt, that is at least 1/2 mastiff and 1/2 Terrier. I'd be concerned less about it may contain Pit Bull and more concerned about the Terrier part of it. Terriers are high energy in general. They have high prey drives, and are GO GO GO GO GO! They normally don't do to well around small pets or other small animals. Normally are great with kids and people in general.
I know nothing about Mastiffs except they are HUGE dogs that drool and are huge teddy bears that will scare the poop out of you in the dark lol.
So... I'm seeing a Large dog that more then likely will drool, that is hyper active and will need to have daily walks at least 1 hour long.
Please don't freak out because it contains "Pit Bull". Take most everything you've heard on the News and throw it out the window.
www.badrap.org is a GREAT Pit Bull resource. That dog is only a quarter Pit Bull, There is a good chance it won't even show the breed in it, which is sad because I can not think of a better breed myself. If it was me, I'd be looking more into Mastiffs and Terriers in general.
Good luck and I hope you adopt him/her