King 2.5 Spring Replacement - Longer 550 Spring Or Same 650 Spring

I am getting my King shocks rebuilt and was deciding on replacing the springs to achieve the same lift height while using less preload. After doing research, I read that using a 650-700 spring will do that since I do have sliders and a catshield/under armor. Would it be possible to get a 550lb spring that is 18" give me a softer ride offroad and give me a 2-3" lift? Would it be possible to fit the longer spring without binding? (factory king 2.5 springs are 3"x16x"600lb)

 

Spring ratings are there to support the weight of the truck. These trucks are heavy. Going to to lower weight spring may leave you with a worse ride than you expect due to the inability to support the weight properly. The valving of the shock has more effect on how soft or firm the compression and rebound are.

 

That makes sense, thanks!! Might just get 650# coils and use less preload and see how that goes since I have some additional weight compared to factory.