Don't need a panhard bar IMHO. You may need a set of Caster Camber Plates to put it back in alignment, or are least some of the offset caster camber bolts. Also may need new isolators. For the top & bottom of the springs.
I went through this on my 96 SVT
Cobra in the fall. I used H&R springs for a 1.5" drop. Midwest Motorsports Cast camber plates, I replaced my shocks and struts with Bilsteins. Replaced the isolators. I added full subframe connectors. I wanted lowered and handling.
People will tell you, you need a bumpsteer kit, lower control arms, and another boatload of parts.
You won't need shocks unless you've put 75K miles or more on the car. Many people get away with just the springs and the bolts. Just get a good alignment after you do it. Good luck.