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...for anyone who just wants to follow the path of least resistance with these pedals, but still use the original crank (mine was a pretty nice one), there's a guy in Russia machining and selling retrofit adapters for the crank holes that will step them down to fit a standard 9/16 pedal threading. So you can choose from the wide assortment of current swell pedals available from MKS, etc.
Shimano Dura Ace AX EX 600AX Dyna Drive Deore Pedal adaptors cranks adapters | eBay
...also this guy in Poland, for ten bucks more:
New cranks pedal adapters for Shimano Dura Ace AX EX 600AX Dyna Drive Deore | eBay