Gary-K
I am sorry that I don't allway's get back!, right a way on advice needed! (Not That My Advice Is Needed), but your talking atleast 5/8th" with Tile and thinset If not a little bit more!!. Will!!, It's not Stone or Marble!!, but you can allway's find Hardwood flooring reduser's with overlaping lip's, In 1/4" segment's!!, and the width to match your jamb's that I see In your Pic!!!. Finished or unfinished wood's. Marble or Stone Bullnose?, I can make thouse with my Alfa blades!!, but not with a drop down lip to the Brick!!. (But They Can Be made For A Price), but not here. But If you decide to go with a surface type bullnose In Stone!!, you could exstend the bullnose a Tile thickness of your field Tile, and finish under It with a 5/8th", or more, what ever the cut might be with the field Tile!!. (Your Lip!!, down to the Brick, and flush with your Stone bullnose!!. If you can keep It a Stone!!, (Would Look Better)
RJF