Floating Feeling?

I have started driving my 66 Cuda now just cruising. I still have lots of work to get it "Road worthy" My question is when i am cruising about 40 or 50 Mph hit a bump or dip in the road creates a floating feeling almost fish tail. I figure its bad leaf springs. When i park my car on a level concrete floor the driver side is noticably lower in the back. Thanks for the help
The torsion bars are adjusted too high. Lower the front of the car.

George