The only way to reduce the rear wheel camber on any of the 500/126 range is to lower the rear suspension---which means that you have to also lowerthe front suspension to balance the ends. There are 2 ways to lower the rear end--(1) fit shorter rear springs and, (2)--the cheap way---cut about 3/4 turn off the rear springs. This was the method we used at Radbourne Racing,and we also retained the original dampers.
On the front you would use a flatter transverse spring, often made with the 'eye' at the outer end (s) pointing up instead of down--known as 'reverse eye' springs. Be careful at the front---you have fiat 600 brakes all the way round on a Giardi, the front upright is probably also from a 600, which MIGHT make the distance between the 2 'lugs'at the bottom of the upright (for the lower king-pin-carrier bolt) to be further apart than on a standard 500.
