Ok So UVB has to be 8-9 inches away. If the basking itself is getting too warm then you want to adjust the basking fixture or get a thermostat that will hook up to it to control temp. The UVB itself is not increasing your cage temps that much. it would be the basking. This is the thing about this type of cage. Controlling temps you have to find the sweet spot. I use a thermostat on my basking fixture. Then I have 3 T5's running. They still only make basking about 79-80 at 8-9 inches down. So you have to get the basking fixture dialed in more. Reduce bulb wattage or raise up the fixture more or get a thermostat for it.This is the UVB light
Its was originally about 8-9 maybe a tiny bit lower from her top branch, now its higher than that due to the basking spot getting to hot (82-83 degrees F) in the afternoons, although it seems to fluctuate depending on the weather and it still can get that warm when the sun is starting to set.
Arcadia D3 6% UVB T5 Bulb - 22"