Just because a dog looks scary and can bark doesn't make it hard, seen dogs you would take a half mile berth of that when pressured crumble and run off. At the end of the day if your dog isn't from the right stock, trained and tested in real life scenarios then you will never know if its gotte mineral or not, an you certainly can't tell if it has because it barks and "acts" aggressive.
Not gonna tell you what breed to get as theres plenty to fit the bill of a yard dog, just do as you would a lurcher and get a pup from dogs doing the job and half the battles won.
Atb J