Smoothing out the ride - Solved

If they're Bilstein RCD's contacting Bilstein probably won't help, RCD modifies the Bilstein shocks for A-body's and improved handling by changing the valving.

Are the springs XHD's? A quick look on summit shows XHD's but not standard springs which have a lower spring rate (80 vs 110 for the XHD's). If you had standard springs on there before and now have XHD's and Bilsteins the ride will definitely be stiffer, it's supposed to be. Do you have the part #'s on the springs?

As far as the springs "breaking in", the ride height might change a bit as the springs sag a little, but that doesn't change the spring rate at all. Unless the springs sag so much they don't function properly the spring rate will remain the same. That's why you can have old springs re-arched.

How tight did you make the shackles? Could be binding up if they were over tightened.