Today I trial fitted the steering rack (well, when I say trial fitted, I actually mean that I shoved it in the front of the chassis to see how it looked). With it in place, I could see that it was too short by a few inches. Also, the trackrod ends are too small to fit the sierra uprights.

I will therefore have to fabricate steering rack extensions like those used on the Haynes Roadster, these will both extend the rack to fit the width of the car, and allow me to fit sierra trackrod ends.