Personally, I would use 2 of the HLG 600r for that area, probably at full power. I use mine at 75% in a 40"x40" tent. Heat isn't that bad but in late flowering it can get higher than I'd prefer but I'm looking at remote mounting the driver. The 650r is soo much more $ for a little extra power.
Also, look into UV lights to supplement your quantum. Has made a significant difference for me.