If you are trying to kill the game for good, go for it. Your problem in balancing is not that the races are too different from another. The problem is that the races are almost identical, except for a few features. These few features are enough to make the races imbalanced, however they do not allow for the range and complexity that you would need to (re-)balance the races. What you need is adding more parameters, more variables, more attributes, to have enough degrees of freedom available to tune the system to your desire.