I have pit bull terriers, lovely pets with strong terrier prey drives, that must be managed. Also have experience with rotties, very serious guard dogs. Mixing these breeds look like a very poor idea to me! You might get a nice pet who guards sensibly, with lots of training, or a dog who's both animal and human aggressive, not to mention stubborn.
Starting off, meet the parents, find out if they are xrayed hip displasia clear at least, and be a very serious puppy and dog trainer!
And a rescue from the shelter might be just fine too.
Mary