Did you REALLY mean *-3* camber? I think that's a bit much. Even -1.5 was on the edge of being too much in my car on a hard launch ("verified" on smooth, clean concrete). I wouldn't got past -2 (of course that street tires, but I'm also thinking auto-x and road course).
I think we are concentrating too much on changing the wrong parts to get a good launch. Yes, stiffer springs will help squat, but can hurt if the don't have the right amount of dampening control.
I personally think that either changing the moment arm that the weight shift has to work against durning launch (read: make the wheelbase longer), or adding more anti-lift to the front suspension, or possibly both, is the way to go.
To change the wheelbase you don't have to go as far as Brian Slowe did...just put on wheelie bars! Honda's and such have been doing it for years and it works! Now, JT might argue that you can't drive around very well with long friggin wheelie bars hanging out the back of the car (which you can make them removable, but anyway).
OK, then time to modify the front suspesion and add more anti-lift to it. This will require either modifying the stock K-frame, or making a custom one. The second choice will allow you to even loose some weight if you choose to do so!
Yes, both of these are not as easy or cheap as springs, but I think they are better options for a good solution. Yes, there are people that have been sucessful without either of these modifications, but I'm willing to bet their set-up isn't exactly the same as this one.