I put the front springs with add a leaf to level the rear out, keeping my stock rear spring pack. Overall lift in front ended at 2". This tracks with what techs at Skyjacker told me for install on cummins (read more weight). Rear add a leaf actually still resulted in a slightly downhill attitude in front when unloaded in rear, but with a little weight in bed or GN trailer hooked up, everything level. Did not have to mod front drive shaft either. However, did have to match shocks to new travel. Do search in archives, you should find numbers I posted.
On issue of weight, the Skyjacker spring pack contains 5 springs, while the OEM is 6. I have stock bumper, no winch, so can't offer much feedback on sag with attitional weight.
Pat