With a cage that size you might want to include a couple of 75 watt or 100 watt bulbs and have them on a dimmer switch in case they get too hot.
I think the hardest part is buying the bulbs and doing trial and error. I have a ton of different wattage basking bulbs that I have aquired over time.
I currently have cages about the same size as your dimensions, but they aren't quite as tall. I use one 75 watt halogen bulb per cage in the summer and I add another 50 watt bulb in the winter. (I live where it gets really cold in the winter, you might not need to do this.)
My first cage I ever built was the same exact size as yours and I believe I used two 100 watt bulbs in that cage.
I almost forgot. I also have all of my heat lights on a dimmer switch, so I can turn them down when they too hot. This helps me keep a consistant temperature at all times. My dimmer switch has become one of my most important cage accessory.
If you don't know how to wire a dimmer switch to a electrical outlet, there are dimmer switches on the market that you can plug in. Actually, Zoomed markets one and I believe they call it a Rheostat and they also have clamp lamps with a dimmer switches already on them.
For UVB light I use Zoomed's Reptisun 10.0 florescent tube that runs most of the leangth of my cage. Reptisun 5.0 and Exo-Terra's 8.0 bulb are also good UVB providers.
I hope this helps.
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Eric Nelson
http://www.beardeddragonresource.com/