Shocks are Shot from Pool Equipment weight, which lift/springs to get need assistance

So I drive about 100 miles a day with about 600 pounds in the back of my truck. Over the course of a year or so, i've noticed the level of my truck dropping. I'm pretty green when it comes to working on trucks, but i'm guessing it's time to upgrade my shocks and leaf springs.

My truck is currently stock, but i'm looking at the bilstein 5100's for the front and i'm unsure what I should to do that back. Do I need to replace the leaf springs altogether? Also, by going up from 265, will I need to change anything around?

I know there are a bunch of questions, but anything helps.

Thanks

 

^Agreed!