[markwilliamson2001]

Basically a rough guide:
Longer links higher on the inside for higher grip, smooth tracks
Shorter lower links on the inside for low grip tracks..

You can fine tune with the height of the link on the inside, changing the length of the link makes more difference. Raising the inner link lowers the roll centre (centre of gravity if you will)...

The rear inner hinge pin height, gearbox height, axle height and ride height all interact with each other though!

Lowering the rear link on the inside can make the car feel twitchy on high grip tracks, raising it can free the car up and cause some 'drift'.
Making the rear link longer makes the rear 'hold onto the turn' more. Shortening the rear link makes the car rotate more (useful for hairpins etc)

A lot of this is down to feel however.

My suggestion is to look up a few setup sheets and see what the common ground is on this, then tune on feel at the track :-)