[cbreez]

That's very ingenious! You are very close on the weights. I have scaled my car with a tank of gas and the weights were 602 lf 635 rf 664 lr 714 rr about 47% front and 53% rear. BTW, if you put a driver in the car you will be close to a 50-50 side to side weight distribution.
I mentioned shock travel because a good rule of thumb is that you want 2 to 2 1/2 inches of travel...so if your springs get you close to that, you are close to having the correct rate in the car.
These cars will never feel like a Caddy!