Dave
In the pick a part yards over here you trip over all the sigma/colts they have. Best of all though was that I've found two SAAS boss's, one for a spare the other I've cut down and used in my the car to minimise how far out the steering wheel sits. This I'd recommend as the all ali boss allows you to cut it down!
In reality, you just need to use the combination that suits your aims. And by combination I mean column, combi switch arrangements and shrouds to suit your taste.
The older smaller cars tend to have slightly smaller shrouds but parts can be a bit weary or hard to find. I've grafted an early 90's hyundai excel combi switch and shrouds onto the colt column because with just a thin layer of roof sheet steel the ignition lock nicely fits on the column. It may be this point that leads what you use in a mixed set up. The toyota options are also good too, corollas particularly and ford lasers.
What do you need in terms of steering lock in WA, do you need it lockable? This might allow you other options such as button start off the dash.
Early colts had only one stalk for indicators, do you want that or the more modern style of two stalks. Choices choice.
My rack was the bog standard shortened
VB commodore I think un powered. Again just need to be able to fit in whatever you choose. Others here will be able to suggest actual powered racks in use, and these would be the best first choices to look at.
Happy researching!!