Chris, 3" springs in my opinion is too far. You wont' have any travel left from the lower control arm bump stop to the frame (talking about the front). Drop spindles are a better solution as they physically move the wheel centerline up whatever the drop amount is without affecting travel. This doesn't mean you won't have other clearance issues though. Other things to be concerned with dropping the front is bump steer and clearance between the tierods and the frame at full compression.
Most of the aftermarket arms have dropped spring pockets in them also. This allows you to use springs that are closer to stock in height as well as shocks. Otherwise if you just drop with springs, you are also collapsing the shock at ride height, so you are that much closer to bottoming something out.
The back pretty much has to be done with springs, but you get into similar issues with shock length so be careful. Obviously the next step in both front and rear is coilovers.
Talk to some vendors about what you want. They will make recommendations to get you where you want. Lot's of choices out there for A bodies now, Ridetech, Detroit Speed, Hotchkis, SC&C, ABC, UMI, BMR, Global West...plenty to choose from.
Good luck
