i wouldn't bother, just looking at the size of the front calipers (slightly bigger then the front R33 ones) you'd probably run into a fitment issue trying to put them on the rear, with bolt hole centers, rotor offest may be off even if you put the front rotor on the rear. also, and i'm not sure about this, but it may cause issues with brake bias.
a couple of R33/R32 rear calipers aren't to expensive, and at least you know they are designed to be a rear caliper.