He looks to be in pretty good shape which is encouraging! Is he able to easily get up onto that basket to bask? If not, you may want to move that to the cool side as a hide and put in a flat stone or angled flat piece of driftwood for him to bask on easily. The Zilla T8 bulbs have an optimal output at about 6'' through a screen so I'd try to get the basking area within that. Otherwise ordering a T5 might be a better bet because they are much more powerful with optimal output at about 12''.