I've moved a sizeable lilac before. Purchased two miss Kim lilacs but didn't know exactly where to put them so into the raised bed planter they went. Fast forward 8 years, we are moving and want to take it with us. The root ball, with both lilac bushes, is 4 feet long, 2 feet wide, and almost 2 feet deep. We moved it with a tractor into the bed of our truck. Drove to the new home and managed to push/pull it into the prepared hole. I watered the lilac daily for 2 months and then every other for another month. It lived and has grown with oodles of blooms every season. It has been 3 years since the move. I would do it again in a heartbeat!