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I can't speak directly about the 280ZX suspension in a Z but we once used that setup in a 510 for rear disks and CVs. It wasn't a bolt in by any stretch of the imagination. I did a lot of research into trailing arms and it seemed like one of the big problems is the toe and camber curves are reversed. If the arms are close to flat in side view when the car is running then a lot of this doesn't matter. Bit if you lower the car and the arms run at any angle pointing up or down then you get a lot of toe and camber change. Any alignment change (toe or camber) will move the suspension pickup points and that changes a lot of other things. Add a lot of power and the car squats getting you into these outer extremes. To get around this we made a custom crossmember that had about half the trailing arm angle (similar to what BMW uses) and fixed the pickup points on the crossmember. All adjustment for camber and toe was on the arms. This along with mounting the crossmember higher in the car allowed it to operate in the sweet spot and worked really well on this 510. Previous attempts with the stock suspension included ever stiffer rear springs, which helped as long as the surface wasn't too bumpy. On my own 510 I tried a Z bar for a while and that really helped with squat and lift. Here's a Sierra example and you can see the fab work to reduce the trailing arm angle. If I were to do it again I would have used the rules that allowed any axle locating device to create an extra arm that would run behind the diff and connect to the trailing arm to control lateral load. Then use the outside mount on the cross member and not hook up the inner mount. You end up with the equivalent of what Subaru uses on many of their cars. Here's an example below, which is from a thread where Richard is talking about what he's going to do on his Z31.