Please be aware that slippage in the torque converter makes this method less accurate than a tachometer input.
This feature is not a substitute for a proper rev limiter in your ignition or fuel system. Different transmissions respond to shift commands differently and with different delays. It's likely that your engine will exceed this RPM setting by some small amount, depending how quickly the transmission responds to a shift command. In the beginning, it's wise to set this feature conservatively. Initially, set this value at least 1000 RPM low, and then gradually increase the setting until you're happy with the resulting shift point.