Go with the arcadia bulbs they are better then the zoomed and will last 12 months before needing to be switched out for a new bulb.I have a pothos, plantain lily, and umbrella in his cage atm so I would probably want a 6500k light as well I think. However, based on that diagram the 6% Arcadia light in a dual bulb fixture seems to be not much better than what I have currently. Should I go for the 12% or 10.0 then?
So he does the raised fixtures in order to limit the highest UVI exposure. This is more important when you have a cham that is screen climbing the roof. If yours no longer does that then you can place the fixture on the cage and account for the difference in the drop within the cage by lowering basking level.
Keep in mind while it may be 2 inches down to get a 3uvi that is where you want the top of the chams back to rise into the light not where you want the basking branch. This of course changes as they get bigger. My adult male rises a good 3 inches off his branch. So where his back rises into the light is a 3 UVI.
So the first question is does your boy climb the top screen?