Block the oil squirters with 6mm dowel pins, and build the 7 bolt. The squirters share the same oil feed tapped off the main galley with the main bearings , and they stick open after time. Oil then takes the shortest route, out of the open squirters rather than feeding your mains. Over time this results in a starved thrust, and voila, crank walk.

IMO, the 2g motor is a better design all around, minus the squirters