Regearing will bring your rpms close/back to stock. Your speedo will still be off as much as your tire size difference from stock. Only on the 6 speed, the speedo gets effected from gearing because it gets it's signal from the output shaft, iirc.

Will a dealership recalibrate my speedometer?

Dealership can now reprogram / calibrate speedometer and odometer for bigger tires.

How do you calibrate a speedometer after changing gear ratio?

Press and hold the calibration button located on the speedometer, start the vehicle, and then release the button. Press that button again and then take the test drive. Once you have driven the distance needed, press the button once more and the speedometer will calibrate itself to accommodate the new tire size.