[Super73]

Do you know the front axle weight?
How about the rear axle weight?

Before we can help you identify correct spring rate, we need to know your axle weights.. Do you have a local scale you can go get the above weights? Weigh the truck with you in the driver seat, front tires on the scale, then both front and rear tires on the scale. That will give you front weight, total weight, then subtract front from total to get rear weight.

Do you have factory front springs? If not, how long are they uncompressed and do you know the spring rate?
Can you tell us how much upward travel you have when you jack it up from the crossmember. Need to know when you start lifting taking the weight off the front tires.

Disconnect the front shocks and recheck. Did it make a difference?

It looks like you do not have factory rear springs due to the coil overs. Any idea of the existing rate? They might say on the spring.
Also what is the length of the spring?
How far are the adjusters turned up? (Bottom, 1/3, 1/2, 2/3, 3/4, top)

Do you have a front sway bar?

Lets start there..