We always pick the female runt if possible. I don't know why.....they had to fight to get what they wanted, I guess, so would GRIT be the answer? We have had some fine dogs in the past. In the aggressive breeds like heelers, hanging tree dogs, etc. the females seem to be not-so-hard-headed. Anyway, that is what we have found. We have had only one male in the past 40-45 years and he was a nice dog, but that was about all. Didn't have much tough to him, and being blue-heeler Aussie cross, he was a bit hard headed. Mr. FH has a great way with dogs, so that helps a lot. He could control 3 working dogs and never raise his voice.
Good luck with your Hanging Tree pup! Lets see a picture when you get her/him.