r/matureplants

We have Spirea in front of our house, 3 large ones a 3 half the size of the large ones. They are 19 years old and have flourished, however (note photo) we are doing away with the large ones and ideally would like to transplant the smaller on in their place. If it dries out enough I shall try removing the root system of the large ones yet this Fall. Do any of you reading this feel qualified to say if transplanting the smaller ones will be successful?