As I recall, the only differences between the A9X and UC front suspension are:
1. the location of the UCA pivot point
2. the stub axles
3. the steering arms
4. the bump stops
No 1 can be changed by re-drilling the holes in the K-member, earlier in this thread it was stated that lowering the mounting point will slightly improve the camber curve and bump steer on suspension dive, but the biggest affect it will have is to dramatically lower the front roll centre, which is not necessarily a good thing unless you're also able to lower the car's centre of gravity (which drop spindles will help with) or mass, or preferably both. The farther the distance between the RS and CG, the greater 'leverage' the mass will have as the CG changes, in layman's terms, the more body roll you will have.
Stub axles are another compromise because of the lower included angle designed into A9X/Hx stubs (the included angle accounts for most of your KPI together with static camber), the lower the KPI the greater the scrub radius, which is most likely terrible already if your rims have a negative (outward) offset. The best option here would be a hybrid stub axle which retains the Torana stub's included angle but raises the spindles like an A9X and suits the A9X/Hx brakes (bigger wheel bearings would be a bonus too).
The steering arms need to match the UCA / stub axle combo, if using A9X/UC UCAs then you would either use the UC steering arms with the UC Torana stub axle, or the A9X (Harrop) steering arms if using the Hx stub axle.
The compression bump stops I believe were extended on the A9X because of the bigger diameter wheels and drop spindles.
So basically everything is a compromise, the brake setup you want to use may dictate the stub axle you have to use, which will also dictate which steering arms you use, but if it was a question of paying Harrop the big bucks to run the A9X stubs, or having the lower scrub radius of the Torana stubs, I know which one I choose, then I'd put the money you saved on the Harrop arms toward a Hoppers brake kit (which suits the Torana stubs).
But that's just me...