Crank pully nut

[Maxo]

I have the engine out for a complete reseal, water pump, and timing belt change but can't figure out how to get the crank pully off without damaging something... The nut is on there pretty tight.
I'd like to wedge something in the flexplate but that seems like it would be an unwise decision. Is it safe to use an impact wrench on that crank nut? Also, what should I torque it to once I put it back on?
Thanks in advance!