Convert string trimmer to edger?

I have a Mac 3227 straight shaft string trimmer/brush cutter. I would like to convert it to an edger. I understand that there are convertible systems and that this is not one of them. What I want to do is disassemble it, remove the string trimmer head, and rebuild it with an edger head. Basically just using the motor and shaft. Is the an edger head model that would fit this shaft?

P.S. I understand that this machine was not designed for this. I wish to try it anyway.
P.P.S. please do not suggest that I get a convertible system. I do not want a convertible system.