More details? This sounds like what needs to be done for the RB-Solieu GB of LSD's. 30 spline LSD center.
Unfortunately I don't have many more details, although not many more are needed. I have pictures sorta... But the Q45 carrier was bolted in and spun freely. I never set my lash, but that could have been done just like any other diff had I gone that far.
Here you see the long nose (88 turbo) diff on the right and the 1990 q45 diff on the left. Never mind the piss poor work station...
Here you can see it bolted into the z31 long nose R200 case. All I did was switch the ring gear. Ok, actually you cant see it bolted in cause I took the picture before I actually bolted it BUT. It works, I promise.
Here it is from the front...
At this point, what I would need is the q45 mating flanges on the CV axles. Then I would have to have a custom center shaft made. WHY? Because the spline on the q45 axle is different than the z31 axle. Therefore the race's or whatever they are called (part that rests on the splines inside the CV joint) are not compatible between the two vehicles. Thus a center shaft with q45 spline on one side and z31 (or whatever the other side you have is) spline on the other. Also don't forget to make the axle the right length. I priced axles and they are typically about $200 a piece. Sometimes cheaper, sometimes more. At this point you can disassemble your BDO half shafts and hybrid them together to make the one you need.
Like I said. Lot of work to gain that extra .9mm of input shaft diameter.