It's a luxury to move established shrubs from the old house to the Battleground place. I would not, but I suspect new owners would cut most of them down.
This is the usual method, dig a trench in a large circle around the bush. Use pruners for larger roots that extend beyond that, for a cleaner cut. Undercut the bush, using a shovel. Gradually sever the bush from the underlying soil, using the shovel.
We had a hedge of 8 mature Lilac bushes against the curb. For the most part, this area will be lawn again. The house shows up better for potential buyers, and they won't be intimidated by potential maintenance.
I'm leaving one lilac in a corner. We already moved 5 of them last month. That leaves these two. These were the largest.
I did prune a few large stems to make up for lost roots. According to horticulturist Linda Chalker-Scott, "It’s important to realize that roots respond to pruning in much the same way as the crown: pruning induces new growth. Roots that are pruned at transplant time, especially those that are excessively long or misshapen, will respond by generating new, flexible roots that help them establish in the landscape." Since some of the lilac roots were wide ranging and needed to be cut, I did so using a sharp pruners. Chalker-Scott also states, "There is no need to top-prune landscape plants if post-transplant irrigation is available...The only time transplanted materials should be pruned is to remove broken, dead, or diseased branches, or to make structural corrections to young trees." It's hard to break that habit. In the case of these lilacs, some branches will killed last year in the drought. They also needed some shaping. Old habits are hard to break. I have plans to move a 10 foot tall ginkgo tree. I will not prune the top of that tree.
It is interesting to observe the root ball. The roots did not extend deeper than about 18 inches. They did extend horizontally, but it seemed that the thickest mass of roots as within 2 feet of the bush. Good thing. The soil is heavy.
I hope we have not killed these nice shrubs. If we did, at least we tried to move them, and they would likely have been cut down in their original locations. If they survive, they will be a nice, mature hedge the first year, and may bloom the first or second years.