The amount of suspension drop, wheel offset, and overall wheel/tire diameter is going to determine how much rubbing you will have. My 'hoe is lowered about 3/5 on top of 305/35/24s and only rubs very little on lock-to-lock turns. I've seen our body style trucks with 22s and 2/3 drops that will rub because of too much or too little offset. Depending on your particular wheel, you could go 2/3 and have issues, or you could go 3/5 and be fine.
I thinks it's been mentioned already, but for brands, DJM, Mcgaughy's, and Belltech make decent kits for our trucks. If you're only going a couple inches on the front, re-indexed keys and a camber adjustment will work ok. If you wanna go lower, it's better to go with kits that use spindles or control arms so you can keep the camber in check. The rear will require new springs and either relocation brackets for the shocks or new shorter shocks all together. You'll need to trim the bumpstops also while you're at it.