[GarterGuy]

Not much a suggestion as a warning. Shining heat lamps through the glass walls of a tank can actually cause them to expand and crack. I had this happen in a leopard gecko tank I once had (it was a 20gal)...so you do want to be careful of this. As far as the wattage, as long as the snake is not constantly sitting in the heated section of the tank, it should be good enough. Your snake will pretty much let you know if it's too hot or too cold. If it's constantly at the heat source, it's probably too cold; if it's constantly away from it and buried or sitting in or around the water dish, it could be too hot. Usually a snake will sit at a warm spot a while to get its self up to "opperating temp." and then move off. If it's just fed or if it's gravid, it may bask more extensively....but will still move around and such. Hope this helps.
Roy