Answer: It is possible that the tree could survive in the shallower soil, these trees are fairly shallow rooted. However, the soil should be humusy, organic, evenly moist yet well drained, and also acidic in order to provide the right growing conditions. There is a concern that it might not drain adequately due to the artificial hardpan created by the roof below.
Also, it is very difficult to successfully dig and move a tree of that size without professional equipment. The roots spread further than the tree is wide and you need to take as many roots as possible. Trees that are dug for sale are usually root pruned to stimulate roots closer to the trunk, but this process requires a year or two, which unfortunately you do not have. The rootball needs to be as extensive as possible and will be incredibly heavy. (Imagine the small size of a 40 pound bag of topsoil and you will begin to see how much weight we are talking about.)
At this point, I would strongly suggest you contact a professionally trained and certified arborist and obtain an on-site consultation and opinion of the chances of this succeeding -- including an evaluation of the growing site after the move. Make sure they have extensive experience in moving trees and are familiar with Japanese maples in particular.
You could also ask them about propagating the tree by taking cuttings and either rooting or grafting them -- or even possibly by raising some seedlings from it. One of these might be a more viable (and certainly less expensive) option.
I'm sorry I can't be more specific or more encouraging and best of luck with your tree, whichever way you decide.
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