Tires, like mentioned, are something to think about with either link or leaf suspension kit. Most of the performance 275-315 tire selection for 17" wheels at this time are short. 18" wheels have a pretty nice selection of performance tires which are taller and fill the wheel well. You may want to consider modifying this before buying kit to lower your suspension further.
The more and more you lower your car, the less suspension travel you will have. A coil-over spring that is compressed to lower the car has that much less suspension travel until you're riding on the bump stop. This is why I'm saying you may want to really consider getting a taller tire in there.
Also, the body can be lowered 1/2-1" to the subframe if you go with an adjustable solid body mount. This approach will lower your car slightly and still retain all of your current suspension travel. I would suggest the Pro-Touring F-Body setup for that. I know PTFB is not a sponsor on this forum and I'm a new member but they also have a really nice looking "Tall Spindle Kit" for 1st gens on their website. You may want to check that out.
http://pro-touringf-body.com/chassis_components.html
Hopefully this helps.