I agree with speckledhen. You have the same setup as I have, the box & light, and it is perfect for chicks.
I think you should use the regular bulb she suggested. Then take out the thermometer and put in the chicks. I think you'll find the chicks are a better guage as far as temp. If they huddle and pile up under the light, they're too cold. If they all spread out to the far reaches of the box and not under the light at all, they're too hot. If they're spread out all over with some sleeping under the light, they're just right.
I would like to make a couple of suggestions, though. I put paper towels over the shavings for the first week until the babies learn to eat the food. Otherwise they will eat shavings and could get sick. Also, I took some hardware cloth and made a cover for the light by just bending the wire around it. You'd be surprised how young chicks are when they start to fly and could get burnt on the light.