Hey I'm new to chams as well but everything I have seen as far as heat bulbs are concerned always lean towards using an incandescent bulb (regular light bulb). If you have already purchased the fixture, maybe you should consider a bulb that has a larger spectrum for plant growth. In the end, you will need to assess your needs based on temperature readings in the basking spot. I went through three bulbs before I found something that worked for my cham. Hopefully someone else might be able to provide some more info.
~John