there is no real way to tell. Best bet would be to check for stall speed and then "flash" the converter. Brake torque the car slowly and when you start feeling the car "coiling" up check the rpms. "coiling" is when the car feels like it wants to jump but the brakes are holding it. Flashing the converter is: Put the car in 1st and "pop" the throttle, tap it real quick like when you would rev at a civic. Watch how high the Rpms go and the take note. That is about the best way to tell.
Put the Emergency brake on,and push on the regular brake.Put the gas pedal 3/4's of the way down.Usually,where ever the tach is at ( as long as the tires dont spin ) thats your stall speed.