That is a Waterman CF, if you didn't already know. I have one, and as far as I know, there are no modern ink cartridges that fit in it. I have heard that the Parker Factory in Janesville still has some converters available. When I got my pen, there were some dried up old Scripto ink cartridges in the box. I just refill these.
EDIT: What the heck was I thinking? PARKER? Sorry guys, I don't know what's going on.