Leaving the heavy trunk branching would have resulted in a neat oak-style tree but you would have had bad trunk swelling and inverse taper with all that heavy growth from one general area of the trunk.
Now that you striped it down to a single trunk line, put it in the ground to gain vigorous growth to heal and develop the trunk and roots. You will want to graft roots if you want a decent base. Spend a couple years working the roots/base and healing the trunk, then you can begin to develop your branching. There are no short cuts if you want it to turn out well.