Steve
On my 2.7, I had no trouble with binding with the usual spacer system. The rubber mount for the needle bearing accommodated the angularity of the shaft well enough.
But isn't the reinforcing cross member mount - one vertical bolt each side into a threaded receptacle welded into the tub - different on the 930? In fact, shorter, so the cross member sits higher to begin with? Which would mean the 930 steering rack, sitting on top of the cross member, will be higher up to start with?
On my non-Turbo tub I experimented with adding some washers to raise the rack even more than the standard aftermarket spacers raise it. It bumped into the tub sheet metal, and put the intermediate steering shaft bearing in quite a bind. I removed the extra bits.
The U joints are designed to fit onto the splines in only one rotational orientation - designed so that the irregular motion of the first joint is cancelled out by the irregular motion of the second joint. All U joints have this motion unless the two shafts are coaxial (in which case a U joint really isn't needed). However if you grind the slot for the pinch bolt in a shaft to make it wider, you can give yourself a bit more axial motion for adjustment than what it came with.
There are two versions of the U joint. Early cars had forged joint housings - the part which clamps on the shaft. Later ones (2.7, for instance) have stamped housings. I think there is no functional difference, and suspect dimensionally they are the same also - the stamping being simply less expensive to manufacture?
Adjusting bump steer out at the end of the steering arm is a better way of doing things, though those kits are a lot more expensive than just two thick spacers and two longer bolts.