The pic I posted are of (Slickrichic )car here a link to his build thread
http://www.camaro5.com/forums/showthread.php?t=379561 Now his car is not lower a lot its all about the tire dia. he running I think there 28" 3/4 tall tires and that what making the car look like it slammed . For the tire stagger I would not be to worries about it on the street . The Z/28 is already lower by about an 1 in the springs to a stock SS so I think to get the look of being lowering it all about the tire dia.
Here a link to a test motor trends did with a Z/28 & 1LE on tires
http://www.motortrend.com/roadtests/..._make_the_car/ now you can run a P285-35 20" front with a P305-35 20" back and I think the car work fine on the street or you could go with the tall tire set up of P275-40 20" front 28.7 tall and a P315-35 20" back 28.6 tall they fill the fender well the best but you get a big tire stagger .