[muzzza]

Sambo, You need longer bolts and more castor. 4 - 6 deg castor should work fine. Having caster the same each side is as important as having it spot on.
I have played around with various settings and found that almost zero toe works best for me. Approx 50' neg camber. I measure toe with 2.0m long straight edges. Set it dead straight, then just a pinch in - perhaps 1mm over all......just to ensure no toe out. Tyre pressure 22 psi all round. I run 245 series tyres at the front. Wll try and fit narrower more compliant tyres next time around, as tracking can be an issue on some road surfaces.

The Holden subframe used in the Harrison sits a lot lower in a Cobra than it does in a Commodore, which means the lower arms are inclined too far upwards to the uprights. Roll centre is too low and bump steer is induced.

Currently working on some ideas to improve front suspension geometry and raise roll centre ( roll centre resides underground at the moment - would like it at approx 70mm above ground) Ideally lower outboard ball joints need to be dropped down another 20mm or so.