I just built a cage for my boa that is about 5 ft long and 54 in. high. If I were to use a ceramic heat emitter, how much wattage would I need to heat one end of the cage to keep it from the upper 80's to mid 90's?
A standard bulb-size emitter will be far too small to properly heat a cage that large. Buy an appropriately-sized radient heat panel (though with a cage that tall it would need to be big or you're better off going with large lamps)