I don't understand why some of you are so against t-tops. I think it would be a great option, and if you don't want it then don't get it. They add a much needed openness element to a car that Ford tries to market as fun.
z28x, t-tops DO add body flex to a coupe. The hardtops were always more rigid. Why do you think that if you ordered the 1LE autox package, it forced a hardtop on you? T-tops are more rigid, than say, a convertible, but they are not as rigid as a solid roof structure. One friend of mine has a 90 formula with t-tops, and another has a 89 formula with a solid roof, and the 89 is definetly more rigid.
If you look hard enough, you can find a base c5 coupe without a targa top. I have seen them in person.
Here are the option codes for a 99 c5.
http://chevroletcorvette.free.fr/1999.htm
Hardtop was an option on the vette.