Frame or chassis options for A bodies

The best way to approach any type of competitive build is to understand
the design of what you have and why it is built the way it is. And why it reacts as it does to driver input. Then you can determine how and what to modify to make an improvement.
Contact patch is #1. It is the only thing holding all applied force.
#2- How much your car weighs at each wheel should then be used to get your spring rates to oppose this force.
#3- Controlling deflection on everything that is not a spring so that inputs are transfered more direct and precise. This needs to be done without adding a lot of weight.
Budget can definetly determine how this acomplished.