Ardy,
The way the cord goes through the base, there appears from the pics, to be a plastic fitting there that the cord goes through. It would protect the cord from the glass. Although I can only see the underside of the hole and not the top, this type of fitting would also lead me to believe it would be designed that way. Most of the conversions I have seen, usually have a rough drilled hole with not protective element. I think that a lot of lamps use the notch in the base because it would just an easier and less expensive way of doing it, but functionally it is really a pain in the ass every time you move the lamp to get the cord in just the right spot so it sits straight....
Craig