I'd go for the drill/tap/slide hammer procedure, if it's possible to center-drill the remaining piece of pivot pin. If it's hardened to the point it's hard to drill, you can anneal it with a torch until it can be drilled. To do that, point an acetyline torch flame to the center of the pin, and get it red hot. Let it cool slowly, and it should be softened enough to drill and tap it. Screw a correct size bolt in, and slidehammer it out. If the transmission top cover is removed and mounted on a drill press table, the above procedure will be a lot simpler.
Jerry

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