The camber compensator was first developed for use on VWs with swing axles. It works in such a way that in a left hand turn, with the right rear suspension being in "bound" condition (pushed up into the fender), the compensator would tend to push the left hand side down to keep the tire in contact with the road. This is the same concept behind the "Z bar" which is a derivation of the stalibizer bar, where the arms at each end go in opposite directions.
The real issue to consider is that in order to make the car handle better you want to limit chassis roll. If you are successful at this, you will automatically solve much of the rear wheel lift problem. This process is always started at the front of the car with a heavier stabilizer bar. If the front chassis roll is reduced to 3-4 degrees, then and only then should attention be paid to the rear suspension. The first I would do is limit the amount of positive camber that can be generated in a way that adds the least amount of weight to the car. (This eliminates the camber compensator straight away) Then, once this is done, either by cables, straps, rods etc., the a rear stabilizer bar should only be added to "fine tune" the overall suspension package.
One note of caution: When lowering the Fiat 600 be very careful how much shock travel you have left after you lower the car. If you lower it such that you take up most of the shock absorber travel of the original length shocks, you will have a go kart (been there - done that, although it was many years ago). This condition of course means that the suspension can no longer absorb ANY chassis roll and you will lift the front wheel (and sometimes the rear wheel) from the ground. This is very spectacular for spectators.
Hope this helps.
Paul Vanderheijden
Scuderiatopolino.com
Good luck