Q:was wondering if you could use the camber kit allowance to use an aftermarket lower control arm with the shock attachment located closer to the spindle attachment point, effectively improving your motion ratio

Not a bad idea, unfortunately the rules makers thought of this and restricted it.  From here:

http://www.rhoadescamaro.com/build/?page_id=260

Under 14.8.I.4:

“Intermediate mounting points (e.g. shock/spring mounts)
may not be moved or relocated on the arm, except as incidental
to the camber adjustment.”

So, if I were to “spend” the camber kit allowance on lower arms, and I lengthened the lower arm by 1″ for instance,  I could choose to add that inch inboard of the spring/shock mount.

This would improve the motion ratio from 9/16 (.5625) to 10/17 (.588), less than 5% improvement.  There’d be about a 10% increase in wheel rate, which would allow for a softer spring.

Of course, anything that helps is welcomed, but after weighing the possibilities, I’ve decided to stick with the stock lower arms (though they’ll get some special bushings) and go with a replacement upper control arm.  I’ll explain the reasoning behind that one later…