I would run 8 of the QB120 boards, in a square layout with a hole in the middle. Power them at 40W each. This layout will give you the most uniform spread, with no hot spot in the center. 320W total fits perfectly on the HLG-320H-24A driver and gives you 35W per square foot.
8 of the QB132 in the same layout works as well on the HLG-320H-36A.