2006 Silverado 1500 SAS?

Hey I have been tossing around the idea of putting a straight axle in my pickup. I'm just sick and tired of going through these gm 9.5's and want to go to 3/4 ton gm 11.5 (rear obviously). I've heard I can just get a 6 lug conversion kit for the rear so I don't have to straight axle it but having a hard time finding anything of that sort. And I know ifs isn't bad I've definitely put mine to the test and it's held up great for me, but would be nice to have 3/4 running gear. The truck has the LQ9 6.0 Vortec Maxx. Over the next few months I'm gonna be doing a build on it and should be getting around 450-500 hp to crank. Also mating the 4l80e with stall to hold up to the power. Which is another reason I'm going back and forth with a straight axle? What do you guys think?