Sounds like you got a good plan. You can use a regular household bulb like you use for lamps. There are variables as to what size you need. You can get a good enough temp with a regular plastic thermometer that you buy for outdoor use. Put it directly under the basking area and check your temp. If it is 85-90 degrees you are good. If it is too warm, try a 75 watt. I would advise to buy a ceramic light fixture. It is more safe than the plastic and you can these at Lowes or Home depot. I would suggest that you replace your top with a screened lid so that your heat light can set right on top of it facing straight down.

Keep us posted
Linda