I had/have a js100 and was trying to find a 1000 neck for it for about 2 years... It never happened. I came across a 1987 540 saber neck... Bolted that on and it played incredibly well. It's a wizard neck though... So I wound up selling it. Not my cup of tea. Eventually I settled on a new warmoth neck... Maple shaft wood, rosewood fingerboard, stainless 6105 frets... Their standard thin C shaped neck. It plays great! But you won't get the Ibanez headstock. Not sure if that is a deal breaker for you or not. Currently the wait for most custom neck manufacturers is a few months before they even start to build yours. But If the headstock isn't a problem for you... Even a charvel 22 fret neck... Or fender neck with a Floyd nut will work for that guitar. However... The bolt pattern may be off. If you're not picky about the shape of the neck... Or radius (considering the JS100 has a 17" radius unlike the js1000...) And you still want the Ibanez headstock You could always try to buy a 22 fret ibanez neck. Like this for example
No repairs or cracks. The frets are good. The neck is straight and truss rod functions as it should. 2.22” heel, 1.69” nut. 16” radius. 25.5” scale. 17mm profile.
You should be able to reuse the hardware from your ruined neck on this one if you're not against having a wizard. Otherwise... If you want a js1000 you may be waiting for a very long time. Plus this neck is a Fujigen... Way better than any js100 neck.