Certified GKH Gardening Expert
It is a well established tree. I would not attempt to move it. The roots will be disturbed quite a bit, and this could definitely kill the tree. If you still want to attempt to do this, I would dig out at least 2 feet from the center around to insure that you get enough roots. Do this in spring right before new growth starts. Keep it watered until it recovers. Just know that there is a chance the tree will die if you do this.