2500 versus 2600 in rear for soft ride

[earl84]

I currently have 2500 bags with Schrader valves on the rear of my 66 C20. I need to get new shocks, since I don't really know how old mine are, and I'm pretty sure they are bottoming out occasionally. I relocated the shock mounts using the old mounts, like frizzlefry and ScotI did.
However, it does ride a little harsher than I was hoping for. Would the 2600's ride a little softer since they will have a little less pressure for the same ride height (I think)? FYI, I live in the mountains in Colorado (jst moved), and have 240 pounds of sand in the bed for traction.