David,

IMO i'd use compresion struts on the car rather than the ARB...compression struts shouldn't affect ride height as they are acting on the TCA's but will give you caster adjustment, vital for a car like yours, i'd corner weight the car get some decent data for the camber/caster and toe in, if possible do some timed runs tweeking the geometry until you can find an optimum position if you feel you need some extra stiffness fit a blade type ARB, that will give you enough adjustment to find a suitable setup....

HTH

Regards

Ian