PB, I've looked at those square grills and have pondered how I would proceed to install a high pressure burner in one.This first observation comes from my own experiments with HP burners. In order for the burner to operate at maximum efficiency it needs air circulation and lots of it. It may be your top vents will supply enough, I won't guess, you'll have to try it and see. If you are using a high conductivity stone three inches may not work, you will have a hot spot right in the middle of the stone, that's bad. The shape of the taller LBE helps the rising heat spread out, though most is directed directly above, hence the reason people use diffusers From a technical standpoint the best burner arrangement would be similar to a regular LP gas grill, not a single very hot heat source but I think it is possible to make a HP work but not without someway to disperse the heat.