Seems thereis no way to compare one kit to another as the shock angles will be different. I ended up with 300 preloaded 1/2" driver side, 275 no preload pass side rear. When I sit in the car there is 200lbs more weight on the driver rear tire than the pass.
I used FOA shocks spring calculator. It only calculates for sag, and there is a lot more than sag that should determine the spring weights, but it's a decent start point.