Thank you both for the advice. As it turned out, there were complications!
It was surrounded by a porch on one side, a cement wall(only a few inches above ground, but continued deep underground) on 1.5 sides, and the remaining perimeter was crowded by plants which were staying, and the house with a big window. I ended up pruning it back per Bill's suggestion as without doing so I had nowhere to swing the mattock.
The tree was much bigger than I expected; I think it had been cut to the ground a couple years ago. The taproot made a 90 degree turn less than 2 feet down, which made things a bit easier.
The ground was very heavy clay, and between that and the cramped quarters removing the tree took 4.5 hours. Once I got it back here, digging the oversized hole to put it in, getting the tree to the hole, planting, and hauling water for it only took a couple more.
The soil it was in was so dense that even the fairly modest amount which remained on the rootball was too heavy to lift; I would estimate over 200lbs of awkwardness. Fortunately I could back the pickup right to the tree when loading, and between the owner and myself it was doable.
When unloading, I could manage a controlled drop onto a flexible plastic sled, which let me slide it to the planting location over the brambles and rocks with relative ease. Like this:
http://www.amazon.com/Paricon-Flying-Carpet-Sled/dp/B004GF150Y
I soaked it after planting, and watered again a couple hours later; will keep on it tomorrow. Fingers crossed.