Hi and welcome to the forum. The motors, I assume because of the "holding torque" statement, are stepper motors. You need to be more precise if you want to get any useful information. Stepper motors are at their *maximum* torque when holding. When driving the torque figure drops rapidly with speed.
Also, the modern stepper drivers can supply much greater current than the design specs so it is impossible to accurately calculate the torque available when working at speed. The figures can be approximated when the controller and motor performance is known.
So let's get back to "precise," as "two of four screws" means nothing to us. We would need to know the diameter, the pitch, if they are ball-screws, Acme or just plain old threaded rod. Also having two motors driving two sets of screws is a recipe for disaster as stepper motors can notoriously lose steps and there is usually no feedback to the controller to tell it to catch up. This will cause jacking and jamming of the platform. Not "might cause," but "will cause."
You need to spend more time learning and understanding the mechanism you are trying to design otherwise you will waste an awful lot of time, effort and maybe money on something that will disappoint.
Happy to help more, but you need a lot more, reading, learning and thinking before you buy those steppers.