With the sheer variety of prodution steering columns available, it is a bit like trying to reinvent the wheel.
The first thing you are giong to loose is the steering lock. Your number one method of imobillisation for the SVA.
Personally I think that most production columns would be adaptable to cover most requirements.
Although I understand where you are coming from with a view for track use.
The column I removed from the Volvo 850 is a peach.
All alloy 300-400mm of sliding spline, this connects to the rack via a couple of knuckle joints.