Sorry, not ZX, but check out this Subtle-Z
Mine is the Velo Rossa kit. It's the 250GTO rebody. I'm sure most of the regulars here are sick of me talking about the VR. But I love it and it is after all, mechanically a Z.
I really cut a LOT of metal off the car. Hood, front fenders, entire roof and rear hatch and both bumpers. That is a whole lotta weight. The concern about the rigidity of the chassis is addressed through a series of welded braces that run front to rear up the side rails, up to the shock towers, across the rear towers and really makes it quite rigid. It's only for the Z, not the ZX. VR does offer a fiberglass rebody for the ZX but you'd have to talk to them about that.
Those of you that want to keep the lines of your existing Z and shave a bunch of weight should look at the Subtle-Z.