Re: If you were going to part together a JEM where would you start?
Well, the neck is going to be the most important part. You need to at least have an original Ibanez neck. Original Ibanez hardware is easy enough to find used or new. Also, you can find a replacement body in nearly any wood you like pretty cheap and paint it to whatever you like. Pickups are also personal preference.
Put up a WTB thread in classifieds for neck/hardware and keep an eye out on ebay. Or, just buy a guitar from Livewire Guitars.