Look for 60mm AC servos, 200w-400w. They are slightly larger than Nema 23 steppers, but not much. A 400w 60mm servo is about 10x more powerful than a Nema 23 stepper.

https://www.ebay.com/itm/263257465942

https://www.ebay.com/itm/122654877079

200W is more than enough, though.