Main issue with IFS lift is that it doesn't allow for the axle to be re centered, moved forward, in the wheel well. The non round fenders, DUMB GM, inhibits tire size without ridiculous lift. Bulge fenders are an option for the silverado guys but not Sierras, and still not really my thing. Long travel kits are designed for 4" of lift but REQUIRE glass to fully clear 35's or anything bigger.
Plans are a Dodge AAM front axle using the factory strut coil bucket on the axle and my frame, a custom coil and fox shock. This will be version 1, and if it lines up correctly it will stay. If it doesn't line up I will buy coil buckets and place them where I need them.Hopefully 4-5" of lift over a stock Denali 1500, which is still shorter than a stock Ram 2500. I will probably run a parallel 4 link, but possibly a radius arm. This I have done on a 2002 Sierra 1500, as well as on a 1990 V3500 crew cab, in the past so that inst the hard part. I will also have to mount a 99-06 steering box inside the frame rails and a power steering pump to my 6.2l, dirty dingo makes a nice kit. Short term will be 6 lug to 8 lug adapters on the rear axle and later down the road I will find the rear axle from a 11-18 GM 2500HD. I will remove the factory flares on the Sierra, the black plastic inside the fender, and roll the metal behind it to open up the fender well. I want to keep it as low as possible on 35's BUT will build it to insure 37's fit.
***Update on the sliders and pics of intended locations. Just need to make the 6 legs and decide on how it will mount to the frame.