A consideration is that the 3200 is a space saver fully inflated, and the 4200/GS is a space saver deflated.
I suspect that the inflated 4200/GS space saver is a larger diameter than the 3200 space saver.
The 3200 may be more tolerable of the smaller diameter than the rear trans-axle 4200/GS, regarding the limited slip diff?
Bolts are different yes, but stud spacing and offset?, 4200 wheels fit a 3200 and the other way around so why won't the spare fit. It may not fit in the boot but could it be deflated as well. I don't know for sure just asking.
Its about the rolling circumference. The 3200's rolling circumference is less than that of a 4200 so what it means is that if you fit it to the front the car will pull to one side and if you fit it to the rear it could knacker your diff!