To get an awesome copy, with maybe some of your own touches, click the LGM banner up on the top of the page... seek out Jeremy.
As for the original neck, Ibanez will want the neck from a Jem in order to send you a Jem neck. There's no bending the rule...lol They wanna see a broken Jem neck for the new one.
I have seen Jem necks come up on Evilbay once in awhile. Check into that...or even get a plain RG neck there, and send it to LGM for a conversion to more Jem-like specs... Or just send yours, unless you wanna keep the original neck, well...original.