Hun, don't guess at the temps. I think temp guns run about $25 and a digital with probe can be bought for $6-$10. He can't process his food unless his belly reaches at least 95-105 degrees and some hotter spots would be good as well.
This is what I mean by a digital with probe. You lay that probe right on the basking spot, wait 30 minutes and see what it says. Then you will know for sure and you can tweak your wattage accordingly.
http://www.herpsupplies.com/product....446&id=ZMZTH24
If you have a bit more money, this site also has infrared temp guns, which are the best means of measuring all of your temps, including your own. lol
http://www.herpsupplies.com/product....8785&id=SZMRT1
Guessing is risking his health, IMO. Temps can fluctuate too, so checking the basking temps and ambient temps on a regular basis, like when seasons change, is a good idea.