ok.. here goes.. I have a kr808 laying around.. i seem to collect e-cigs.. running an e-cig business and all. but A 901 atomizer DOES fit them and i have heard they do fit the vapor king. I have actually used a 901 battery on a cartomizer, but the draw was horrible.. couldnt activate it and get air through, but the other way around with the 901 atomizer and the vk battery should work in theory, but you may have to take some tweezers and pull down the center of the atomizer to make sure it makes contact with the battery, I will try when i get home from work to see what happens.
Jason