Pat, how many bricks are you using in your diameter? 14? And are you 2 bricks tall (18”)? Mine is going to be a very similar design to yours too. I’m gonna try it out initially without any hot face refractory. My top and bottom bricks will be cut exactly the same. They should have a 2 1/2“ x 2 1/2“ x 4 1/2” off cut which I will add to the walls which will make the walls 13 inches tall. Outside all the brick I’m going to add the 2 inch fibre blanket This is my rough sketch.