Traction loss in corners (on rough roads) can be caused by several things...stiff springs, worn shocks, spring wrap-up etc.
A better design shock would help. Shocks are designed to keep the tire in contact with the road. An old lever-type shock has severe limitations in this department. A shock that has adjustable jounce and rebound would help.
Adding one 1/2 leaf to the FRONT of the spring is an old drag racing trick designed to prevent leaf spring wrap-up on acceleration. MOPAR racers that use leaf springs use 'super-stock' springs designed just this way.
Ideally you would have a nice, soft compliant spring just stiff enough to discourage bottoming out mated to a shock with adjustability. In the world of dirt track racing soft is fast.
In reality you have to understand that you are driving a car with a suspension system designed over 60 years ago for satin smooth roads. In that case, a softer touch with the throttle is the usual cure...