lowering an 84

Where can I find lowering spindles for my 84? If i just got lowering springs how do I align everything back up? Im also trying to find a decent set of wheels for this thing. what would be a good backspacing to use for a set of 17X8.5 wheels. Im really digging the torque thrust II Wheels with the gray center.
If i put a 4L60E Would I have to change X-members? I have the 700R4.

Be careful lowering..I know my Caprice woudl bottom out real easily when the shocks went bad.

Then that means I need shocks desperately because my car just about hits the bumpstops now!