67-68 lift kits (rear leaf compatability?)

[hifiguy]

I've got a 68 suburban that I want to put a 4" lift kit on. I don't want to use rear blocks as my springs are a bit tired, so I'd like to replace the rear springs. The problem is that supposedly the rear springs from a 67-68 are different than 69-72. I was wondering what kind of lifts everyone is using in their 67-68's, or what kind of modifications are necessary to fit a different spring in. Mine is a 1/2 ton, and I would like to use a softride type spring not heavy duty. Any recommendations would be helpful. Also what kind of front springs are decent? And finally does anyone have a front driver side leaf spring mount for the front axle of a '68 for sale? Mine has been replaced with one that is not correct and I'd like to fix it.