[JLMounce]

The bigger question is how do you use the car? Depending on how it's used and what you want it to do, really dictates what you should be doing.

The A-bodies are horrendously under-sprung. If I was looking to do any type of competition out of these things I wouldn't even be looking at spring packages less than 600 lbs in the front and at least 175 lbs in the back. I even believe you can still maintain a quality ride at these spring rates if you opt to use drop spindles instead of lowering springs.

My guess based on your post is that you're looking for something just a little more sure footed in what is an otherwise street driven car. In that situation I would simply go with the 1" drop springs front and rear. Since this likely isn't in any type of competition, the changes in the rear shouldn't be severe enough to warrant changes to the rear control arms. The car from the factory is so undersprung that there's a ton of movement back there anyhow, you're static position will just be changing slightly.

If you intend on a lot of drag racing, you want those weak factory pieces out of there anyhow. At that point going to an adjustable upper will help get pinion angle back to a favorable place.

For the rest of the suspension, upgrade your front sway bar and add a rear. I like the hellwig stuff for that.

Pair it with a good set of shocks. The Koni Classic (Red) is a good mid-level shock that can be serviced from the bottom of the control arm without having to put the shock on top of the control arm

Finally, add a modern alignment. -.5 to -.75* camber. As much positive caster as your factory arms will allow. 1/16th" to 0 toe in. You can do a road crown alignment if you've got heavily crowned roads in your neighborhood.

If the bushings in your car are original, consider changing them.

This type of setup is going to provide you better tracking, more grip and feel less like a boat, without impacting ride quality.