spray WD40 on it and let it sit. Whack the threaded end of the pin with a hammer and a block of hardwood. I put the nut at the top of the threads to protect them... may as well plan on bending the pin and having to replace it.
The crank has deep grooves, 180 degrees apart for the tapered pins. If the pedals arms are way off pointing 180 degrees from each other, something is messed up bad..
just try to not bend the crank.. the other stuff can be swapped with bicycle pedal stuff.