Randi, it's really hard to help you without a detailed list of your symptoms and the car's history.
Are the springs the problem? From what I can gather from your posts, it doesn't seem like it. Weak springs could cause the car to run poorly and idle roughly, but they would have to be pretty worn out to keep your car from running. If it will run with the ZS carb installed, hook a vacuum gauge up to the manifold and fire up the car. Once the car fires up and and is running steadily, look at the vacuum gauge. If the needle bounces around erratically, it could be your springs or some other issue with your valve train.
I must stress that 90% of all "carb" problems can be fixed by repairing the ignition. Are you absolutely 100% without a doubt certain that your ignition components are in working order?