Suburban 4X4 suspention question

[SoCalSlaughter]

I have a 1990 Chevy V2500 3/4 ton 4X4, and I've noticed that the front leaf spring are sagging. "sad smile" I want to swap the leafs out to at least make it level or have alittle bit of a lift to it. I dont want to have to change brake lines, and drop the transfer case and all that. My question is should I run a 2" or 4" lift spring in the front. Ive heard I can run a 4" leaf spring in the front without having to mod the exhaust and brake lines and all that except maybe the steering. I dont use the truck for crazy off road, only in sand and mud/dirt.