[projectRDM]

Mike, you cannot use the S13 stud in the Z32 upright without significant modification, IE welding a portion of aluminum into the upright then drilling/tapping for the stud at the correct angle. This would eliminate the need to use Z32 shocks in the rear but I've never met anyone willing to make the effort. The angle alone is your main concern as it would need to be precisely set up to match the S13 upright under both full load and unsprung load. Since the Z32 upright already sits at an angle it'd be hard to get it perfect. The spherical bearing in place of the bushing is the more ideal situation all around, you just have to use Z32 shocks. Some people don't like going that route since the Z is heavier and therefore the shocks are a different preload, in that case you just go with coilovers and matching Z32 fork mounts.

As far as urethane bushings in the uprights, these don't wear near as bad when used with arms that have spherical bearings, as the arms do allow for more twist than a stock arm. The better setup would be spherical bearings at both ends, but the cost and ride comfort level are heavily effected. You're going the better route by using the Nismo bushings since they're still compliant to an OE level but with reduced flex.