73 nova suspension help

well I have a 73 nova hatch back with a 350. I put in the stock shocks for the 350 when I put it in and I have generic air shocks in the back. I am now looking to upgrade front and back suspension. I want a nice firm ride in the front, not too much dipping in the turn and I would like a firm ride inthe back as well. I dont know too much about suspension so any help would be great. Also the car has the original leaf springs, I have not spotted and cracking in them. They do have a good amount of surface rust, what would be some keys to check if new springs r required.