Yea... the main challenge so far will be fitting the combustion barrel (which I still don't even have yet
) in that space. The rock arch restricts access because it is built so low. Basing the measurements of standard 30 gal steel drum (18"x29"), the hearth, mortared together with large pink-orange-brown rocks, will have to be removed, and then rebuilt. Final positioning of the barrel will be directly up against the steel back plate of the firewall in the fireplace, where it angles toward the arches. Next step: remove the hearth stones with the Bosch hammer drill, which has been the handiest tool, so far, for busting up and removing mortar.