Another update. I'm posting as her now Still haven't adopted her as there are some issues and they don't click completely, but at this point I'm motivated to help with her aggression whether I keep her or not.
HUGE improvement though. She will still growl from time to time but the two are playing now. They'll tug at a toy together with one dog on each end. They also will sit for treats together without one getting mad at the other. The key has been exercise, exercise, and more exercise! I'll feed and play with them after an hour's long walk and afterwards they have even crashed in the same bed