I agree with 39 master. Get the car weighed front and rear. Try and get a straight on shot of the suspension on one side.
Just looking at this picture it looks like an aftermarket chrome spring. These only come in 375, 500,700 pound ratings. They are short than stock to get the ride height down. In any event it’s important to get the lower arm parallel to the ground. There are dropped spindles available from a number of suppliers to help this.
You can also use an anti roll bar. There are several available.
For now that’s about all we can do until you give us more info.
Typical coil over shock conversions like this are very stiff. I’ve had my adjustable shocks revalved a couple times but they still were very stiff. It doesn’t look like yours are adjustable. There would be a small knob at the bottom by the control arm.