It looks to me like a chassis problem causing at least some of the move to the left. Focus if you can on your steering wheel on launch. If you see that you are not turning the wheel a lot, then something is unloading the left rear tire a couple of feet after the hit. Short shocks? Wrong preload?
As far as rpm, I would start at 3,000 rpm and see where things are. 3,000 should give you a consistent leave, and let you know what you need for proper chassis reaction time.