4" is fine. my truck dosent look bad with 31's (sas & 4" rear springs). if you want articulation for cheap do chevys. and move the spring perches.
if you arched chevys to fit in the stock location you would end up with something like 15" of lift.

or you can buy some 4" lift springs like i did originally. but the will not flex for crap, and ride like ass. (at least my skyjackers do).

personally, id try and do an add a leaf to you stock pack, with a longer shackle and maybee a 1" block if you need it. that would be the cheapest solution. forget arching the stock pack, its not worth it.