FYI, FBinNY was a distributor for many years, and sold Jacob's chuck wedges (used for removing drill chucks from tapered drivers) for shop supply. They are invariably useful to have on hand, and would remove your cranks without fanfare. They are (I presume) available from some other company worldwide, but they are super common in the USA. A #6 is about right.

A local machinist/woodworking shop would likely have them, and may even take pity on you and let you use them. Harder with a long-nose punch (which you'd need here), rather than a large clamp/vise, but doable, nonetheless.