Before I give you a reco, you need to know that these cars
need some negative camber in order to keep the tires from wearing the outside edges during any spirited cornering. This is even more true when the car is lowered, because the outside tire will gain less negative camber as its strut compresses than it would if it were at factory height.
The problem is, everybody and their brother will try to scare you away from negative camber because they say it causes the inner edges of the tire to wear. This marginally true, but nothing you're going to notice in 20,000 miles. The
real tire killer is improper toe setting, or the inability of the
suspension to keep the setting when the car is in motion (e.g. weak A-arm bushings). If the toe is wrong, it'll wear the tires in a hurry, and it'll concentrate that wear to the edges due to camber.
So, with all that said, set the car to 4-5 degrees positive caster (or as far back as you can get the plates and still get the camber you want), set the camber to at least 1.25 degrees negative. I prefer 1.5 to 1.75 for general street duty. I actually run 2.25 neg at all times during track season (8 months of the year) so I don't have to dick around changing it back and forth for the track.
The key is, I re-set the toe whenever I change the camber. So whenever you have your camber and caster set, then set the toe to absolutely zero if you have urethane or delrin A-arm bushings. If the bushings are rubber, give it 1/16th of an inch of toe-in, because the bushings will deflect when the car is rolling and bring the toe out closer to zero.