Thank you for the reply! Then once you have threaded the pen for a JoWo, will this still require heat setting? And were you able to screw in the nib from ASA?
If you buy the pen with threading to fit a JoWo nib, you can simply screw in a JoWo nib unit - no need for heat setting etc. If you buy it as an eyedropper pen with Indian nib and ebonite feed, you can swap out the nib for a JoWo.
That's where heat setting comes in: heating the ebonite feed so you can adjust it to fit the contour of the replacement nib.