Mysterious Ferrari Pen

[JEBS98]

Hi there! I wonder if you can help me out of a mystery. I have this very old fountain pen. It was bought in Italy decades ago by my grandfather, who always used it with cartridges, but these are now impossible to get. I decided to try to buy a convertor to solve that problem, but I just cannot find out which is the manufacturer of the pen, and thus I do not know if I have to buy a proprietary convertor or if a universal one will do the job. The only brand on the pen is "Ferrari", because it was an official licensed product back in the day. However, there are a number of manufacturers that have worked with Ferrari (Sheaffer, Montblanc, Montegrappa...). The nib is not proprietary, since it is made by Iridium Point Germany. Does anyone recognize it?