"Looking for a motor pulley" Led me to assume your drill press had both a 'motor' and a 'quill' pulley with each the (vertical) mirror of the other, each comprised of three or four pulleys each a bit larger than the one below (or above on it's mirror). And, since you wrote that you were looking for "a motor" pulley, I further assumed that you had the Quill Pulley in hand and, thus, could easily measure the quill pulley to determine the diameters and other measurements required of a mate to fit the motor shaft.
Frankly, unless there is some need to rebuild the press so as to achieve the exact speeds available 'from the factory,' you likely would not need to match the diameters of the Quill Pulley exactly.