While you could use a motor and a screw to accomplish what you want, the control system would be rather complicated and expensive.
It sounds like you are just building a press, so a linear system would be more appropriate for the task. Since you only need about 300 lbs, a 2 inch bore air cylinder would give 314 lbs of force at 100 PSI. The advantage to an air cylinder is that the force is easily adjustable with a regulator.