rear battery relocation question ?

67Dart273 nailed the whole NHRA aspect of this (not that I agree with them on switching the + cable... Maybe someone here can give me a GOOD explanation on that. But hey, rules are rules.).
Now, weight distribution? Why would you want to add weight on your already heavy drivers side? No offense, but YOUR body weight is already there... and you're not changing that fact too easily... Your left/right weight bias would be better with it on passenger side.
Another thing 67Dart273 hit on is engine rotation. Your rear axle isn't just applying power to the wheels... The whole housing is trying to rotate under your car, just as the driveshaft is. That's the reason open rears light up the right rear tire. They're planting the left wheel hard and actually trying to lift the right.
Just a little more food for thought.