They are survivors! I have moved much larger ones, with only a 3 ft. rootball, from shade to a sunny location. I pruned them severely, about one-third of the branches, including all of the crossing ones. Fall is probably the best time, after defoliation. After moving, water in well to remove all air pockets and mulch with about 6-8 inches of bark, leaves, straw, conifer needles, etc. Leave an air gap of several inches around the trunk. If the winter is dry, be sure to irrigate the roots periodically, especially before a hard freeze. You may lose the flowers the first year after relocation, but flower production is at the whim of Mother Nature in Zone 7 anyway! I lose the flowers most years to a hard freeze, just as they are beginning to open.
Good luck!
Rb

As mentioned above, flower production in z7 can be a problem. We seem to be in a zone that sees an "extra freeze" after a couple of weeks of nice weather. Ironic really; They are probably good in z6 and z8!

They seem to be adapting well to the yo-yo temperatures this year, for a chamge. My M. stellata amd M. loebnerii ' Merrill' is blooming quite nicely now. This is the first year, for a number of years, that we have been able to enjoy them!
RB

I would move it with a tree spade immediately after blooming. Worthwhile to do as they tend to be somewhat pricey trees.