Ah - ok. It was just that I was getting confused by the fact that you mentioned XR3i arms, which as far as I know are track control arms with the roll bar used for for-aft location, instead of the two mounting points on Festa wishbones.
Ive seen some adjustable wishbones from TAS Motorsport which are proper rallying ones, but theyve got rosejoints which I wouldnt use on an everyday road car unless you like a rough ride and regularly replacing them.
I thought it would have been cheaper (and better in terms of camber control) to slot the top mount (i.e. make a new one) to adjust the camber. Although Ive never taken Festa struts apart, you may be able to slot the pinch bolt hole where it squashes in to the back of the hub - I think Leda suspension and old mk1 Golf struts were like that. If your car is lowered, your neutral roll-centre will be too low anyway relative to your c of g, so by moving your strut out at the top, it might help raise it a bit. Hope that helps.
Steve