How to determine the needed stall speed?

For a drag car I generally like the stall speed to be 1200 to 1500 RPM less than my shift point. My dart gets shifted at 7000 and the stall speed is 5800. I ran a 4000 stall when the car was street driven with the 360 motor. I run a continental converter.
[ame="http://youtu.be/t0OVIsU01mg"]302 Found[/ame]