Based on your post and photo’s it would appear that so far you have slip potted the plant. Basically, put it in a larger pot with looser soil around the original rootball. The photo’s appear to show some rocks and old soil within the center rootball. If that is the case i would reccomend repotting this spring to ensure fresh soil and proper drainage throughout the entire rootball.
Then, let it grow free and judge its condition after a year of growth. This would prepare the plant for future work and improve its general condition.
Just a word of caution, when trees have been slip potted , one needs to be careful with watering to ensure that the actual rootball is properly watered. Too often the watering drains quickly past the rootball in the new looser soil surrounding. One tip would be to soak the entire pot in a basin of water when the center seems dry.