Shocks and springs

[1965 Mustang]

I have a 29 leatherback. It is a good driver, but the ride seems pretty harsh.
The springs look ok, but when I jump up and down on the front or rear bumpers there seems to be very little movement. (I weigh about 260 pounds)
I suspect something is not right, perhaps the shock arms are frozen or nearly so. Any suggestions? I guess I could disconnect the shocks and see what happens. Thanks