That's a nice truck, very similar to mine!
In my 07 Sport after I cranked the torsion's up for a full 2" lift that just levels it. My back end is still sitting about 1" higher off the wheel then the front and I haven't touched her back there at all(well, at least not my truck anyways...).
Did you really need the blocks in the back and what blocks did you use?
As far as the keys are concerned, I replaced one of adjuster bolts to be able to really crank on my T-bars to get the full 2" lift I wanted out of it, and I have noticed the ride is a tiny bit bouncier but the difference is really marginal. From what I gather though, it seems to be different for everyone depending on what bars are in your truck.