Hard steel pins can be annealed to soften them by getting the pin red hot and allowing it to cool slowly. Using a small heating tip on acetylene torch and concentrating the heat on the pin will heat it up without damaging the cast iron case. I'd suggest trying to do some annealing before you start drilling, if you choose to take that approach. Once the pin is out, you should consider threading that hole and retaining the shaft with a dog point setscrew instead of a pin when you do the reassembly.
Jerry

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