Happy new year too!
I have been fiddling around with all manner of suspension modifications with the Sud- and still have some way to go!
My car is primarily a road car although it does get used on the track occasionally. My modifications are limited by the strict regulations for Alfa club events.
I am allowed two modifications in my class, as my car runs a 1.7 it is counted as one mod already. So for suspension I am fairly limited. The car therefore still runs at standard (TI) height which is kind of good for road use anyway.
Shocks are free so I have Koni Yellows front and rear. Front springs are standard TI with 16V top strut mounts and some more negative camber! I have a few different choices of rear springs, standard, standard with "coil lockers" which stiffen the rate as well as some stiffer standard height springs.
One of the biggest advantages of stiffening the rear is that it reduces the "sud squat" on acceleration and gives a lot more traction both in a straight line and out of corners. Also reduces the roll but doesn't help the ride much!
I have a 33 front anti roll bar and crossmember, although you can use the existing bar and fit spacers as you suggested if you can find bolts long enough!
The 33 crossmember alone doesn't alter the castor though, if you fit 33 lower arms (eg. to fit outboard brakes) it moves the lower balljoint and will substantially change the castor.
As the front bar is now above the crossmember it is a pain to remove and I leave it in- I quite like the way it drives and turns in. But it is definately slower on tight tracks- it gives full on tyre howling understeer.
Although I didn't fit the power steer, I can highly recommend fitting the late 33 tie rods which allows simpler and much more accurate wheel alignment. Unfortunately I don't think any Australian cars were late enough to be fitted with these Simon so you may have to look overseas for these (mine came from NZ)
For my 'modification' I fitted urethane bushes to the rear panhard rod, lower trailing arms, front lower inners and centre bushes.
I didn't urethane the front bush as it is designed to flex sideways and if there is insufficient movement the front arms will break (I have seen it happen)
I have fitted 15" wheels with 195/50's for road use although the car is quicker on the track with standard 185/60x14 wheels and tyres. There is a better choice of racing rubber in this size if you are so inclined (but I have to run road tyres in my class anyway)
As a road car it is great fun, predictable and happy to light up the front tyres at will! Funnily enough since I stiffened the front, even with more negative camber (and track use) tyres seem to be lasting longer!