The last month or so I have been playing around with the designs for a full size 4-4-0. Using this fictional locomotive as a test bed for ideas and concepts. In this (dated) sketch I have a Lempor ejector and an Altoona Firebox. I have a few concept drawing of this locomotive in mechanical form.
I like the Altoona firebox simply because it's low slung roof provided a funnel in which to rapidly move hot gasses forward. They where notorious for burning VERY hot. I have been debating trying to couple the Altoona Firebox with some thermic syphons. Perhaps the low slung firebox will help induce a circulation of water to compensate for the lack of heating surfaces.
I also wonder if the Lempor is being restricted by the screens and shape of the diamond stack, even though the diffuser empties directly into the crown of the stack.
I'm sure I can get a few ideas on this from some more knowledgeable folk.