It appears to me that the blackest possible district outside metro Atlanta would stretch from Augusta through Macon to Albany, with some wiggle room as to the exact borders. It could generally follow county lines.
But there would be enough constituents south of the Black Belt for only 2 seats. That would put Kingston and Barrow in the same district. Barrow would carry Savannah but that’s about it. Then Austin Scott would get SW Georgia.
Metro Atlanta would still get a new seat, but the other one would likely have a Columbus focus. House Democrats did carry Muscogee County by 7-8K votes, but did well enough outside that county to hold the advantage.
I made a slight miscalculation — it’s more like 2.5 seats south of the Georgia Black Belt. So you could give Barrow and Kingston their own seats, and then let the new 8th wrap around the southwest corner — Quitman, Clay, and Stewart are Dem but only a few hundred votes — easily outweighed by Decatur, Grady, and Thomas. The new 2nd goes from 48% black and having to add 60K residents to 55% black, breaking few if any county lines, and nearly ideal population.