[71Corolla]

If a 700 pound impact is not doing the job then jamming a screwdriver into the flex plate is not going to work. The starter bump method is safe when done right you can try it but it sounds like the bolt is on there extremely tight. Maybe take the car to a shop to see what they can do with their air tools.

Putting the pulley back on is easy your impact should have no trouble getting the bolt to spec.