Duh - you're right Denis, I forgot about the Grabber II! Even though I have one.
Epi brought out their Ltd Ed "Ripper" (more a GRipp3r really, but a nice bass) some years ago, a non-form, rectangular case with huge compartments was available for it, though not widely. My Prototype has one though, it fits well even though the Epis have slightly larger bodies, they obviously copied the very first Rippers for them.
Look, if you run into issues getting a Grabber case that fits I can dig out one of my old ones and exchange it against your G-3 gig bag, I'd rather have a gigbag than a case. Once my G-3 is here, I would test it with a case that fits snugly and send that to you.