scotty, you would probably first need to determine the critical dimensional differences of the new unit and then measure your current set up. You will most likely need to make some adjustments to your mounting as the new unit will most likely be smaller – hope this help you out buddy!!
The old 585 frame is no longer available, today that motor would be supplied in a NEMA 586/7T frame.
Please note that the motor will be smaller in physical size and consideration would need to be taken to mount the motor in place of the Thompson. Also, this motor would be a lot more efficient!