The coil-over kits in the $400 range don't seem to include traction bars. You can install coil-overs, but you still need something to keep the rear axle in position. The coil-overs take care of up and down. You need something to take care of front-back and left right movement. My last conversion (72 Chevy Pickup) to coil-overs used Morrison coil-overs, ladder bars and a diagonal track locator. Check with Morrison or Chassis Engineering. If I were doing that one again, I would use a triangulated 4-bar.

If you want to drop the front, you can use replacement springs for a 1-2" drop. Cutting the originals is not a good idea - although most of us have done it in the past. If you go much further than that with springs, you'll mess up the front suspension geometry. In unequal A-arm suspensions like the Camaro, the lower A-arm is supposed to be parallel with the ground. If you move too much from that, you get steering problems and tire wear. It's hard to pick the correct spring, though, without knowing the weight on each front corner with the engine in place. A spring that the catalog says will lower your Camaro by 2" may not lower your car a similar amount.

On the rear suspension, coil-over kits are really adjustable. There are usually several attachment points on the lower mounts, as well as several inches of adjustment on the shocks themselves. The coil-overs on my '34 have three different mounting points, and I could have added a couple more. That gives 2" adjustment. Then the shock has about 3" of adjustment in the lower spring location. The body of the shock is threaded so that the lower spring retainer can be screwed up or down about 3". That gives at least 5" of adjustment, depending on the original mounting position. Some coil-over kits also have several upper mounting points. Check the photo.

Here's a homework assignment.

http://www.artmorrison.com/techtipstwo.htm

http://www.artmorrison.com/tri4bar.htm

http://www.artmorrison.com/compstreetladder.htm

http://www.chassisengineering.com/rearsuspension.html