I'd use a waxless adapter - Fluidmaster makes one, and there are others.
You know, the better thing would be to reset the flange to where it is supposed to be. An alternative might be to add one or more flange extenders to raise it to the proper level, then use a conventional wax ring.
Having a deep wax seal isn't as strong as when done with a flange at the proper level. The waxless systems rely on O-rings to make the seal. I've used both, and have not had problems with the waxless. They cost more, but are a real benefit during remodeling when the toilet may be removed periodically.