Semitsu balltop on a JLF shaft

Hi all, I'm looking to swap out the balltop on a pair of Sanwa JLF joysticks, but I can't seem to find a clear sanwa balltop. Semitsu's bubbletop looks good, but I don't know if the threading on the balltop is the same or if it requires an adaptor.

Also, any recommendations on a place to order besides Focusattack.com would be appreciated. I love focus attack, I'm just looking for different items.