For my money Kennedy makes he nicest stuff out there. With that much torque (assuming it will in the high 400 ft.lbs) You may want to talk with them about the clutch. You might want to look Patricks CenterForce offering. You also might want to serisously consider an oil cooler, at least. I would also recommend having the return from the cooler spray on to the ring and pinion, again, at least.
Shock loading the box with that much power is what will break it! Make a promise to yourself that dumping the clutch is off limits and you should enjoy you car for years to come. You may want to consider Redline Shockproof gear oil as well. If you are using a clutch type LSD (stock type) add just enough Redline LSD additive to stop clutch chatter. GM's addititve is also well thought of.
Lynn