I bought a Chinese brushless sewing machine motor and controller for ~$140.00 USD, from Atlas Levy. They are all over Aliexpress and similar for about the same price. I don't know how long it will last, but so far it seems like a great match for the Taig. A similar arrangement with VFD and three phase motor would be in the neighborhood of $500, though it would likely be higher quality. RPM range is 300-3000 rpm, or about 150-1500 rpm with the pulley attached.
The box is made of 18mm birch plywood. All the joints are rabbeted for good luck.
Cable tie hooks:
In the above photo you can see the speed control potentiometer (actually an optical sensor, I assume) and its actuation lever. The lever has a big socket at the pivot, press fit onto a nub on the lever, as well as the two screws and nuts you can see at the bottom. In other words, it is very rigidly attached. This lever is normally connected to a sewing machine foot pedal via ball ends and an adjustable linkage.
Above two photos are the lathe mount, made of hickory. It doesn't match the lathe like the old aluminum one, but it is SO much more functional. The screws which attach it to the surface underneath point inwards for easy screwdriver access.
Here is the