There are a handful of motors that will work, with the Kollmorgen highest rated amongst them, but also hard to acquire and quite expensive by comparison. The inexpensive options are the Chinese-made Mige motors. The so-called “small Mige” has a lower power rating, so produces less force on the wheel. If my experiments to date are any indication, that additional force is not needed. 😮
There is a compression fit coupling that provides the platform to which the wheel or quick release is attached. The Simucube kit from SimRacing Bay included the 6-pointed star-shaped 70mm adaptor seen in the images. The 4 bolts in the center clamp the coupling to the shaft.
But, since they stick out further than the surface of the 70mm adaptor plate, I needed to make a small spacer about 5/16 thick to prevent interference with my steering wheel mount. Found some scrap wood and used a 3 1/4 and a 2 1/8 circular drill bits to create the spacer.