I saw the homeowner at the jobsite today and talked him out of the glued bluestone idea. He wanted to use a couple spare treads he had around from when he redid his front entry. They were 'old' looking and still had a lot of cement stuck to the bottom. I explained that we wouldn't get as good a bond as we would with something cleaner and frankly this two treads would have made the job look hideous.
Thanks for the advice. I know I'll use it in the future.
Especially the angle grinder idea. Nice.