Tire pressure? Air shock pressure?

Your front tires are close to stock size so 28-32 psi. The rear slightly lower since most load is on the front axle. The absolute proper way would be to have the car weighed with the front and rear done separately to give you the actual load on the front, rear axles. Then the pressure can be exactly determined with load carts.
Absolutley proper repair is to replace the rear springs or add helper leafs.
The shock mounts were not designed to carry weight, Some people are under the assumption that shocks do carry weight. Not so unless they have external springs or airbags.
Ok for a truck with HD mounts but never a car. Will only cause chassis damage.\
Pre radial tire cars were built with softer springs to lessen the harsh ride of bias ply tires. The sidewalls were very stiff.