I don't see how an oval chamber can cause better circulation than a round one but there're a lot of things I don't see. Long and narrow like that would probably work better with two 1/2" T burners or two outlets from a blown unit.

I'd orient them somewhat tangential to the wall to induce a vortex.

Frosty The Lucky.

 I have a couple old forge bodies that I retired which I think I will press into service as test subjects. Maybe get a better idea of what will work before I setup and pour the refractory on my final draft. Thanks for the insight Frosty!