I know the typical small
rocket stove has an L-shaped flame path, but why do you want to use that style in a larger indoor unit? The J-tube has been found to be more efficient in combustion, it self-feeds as long as the sticks in the
feed tube last, and its ergonomics are better adapted to typical American stand-at-the-stove practice. (Cooks in third world countries the rocket stove was developed for tend to squat at the fire to cook.)