It could have been assembled with a cryo fit by supercooling the column and pressing it in. If the base plate produces straw yellow sparks when ground then it's probably cast iron. If you scored a line about halfway through it on opposite sides and then around it where you wanted it cut off you could probably break it with a cold chisel and a hammer. Cast iron's strength and hardness are in its outer skin and the interior is much softer. Getting that indent onto the new top for the rack to ride in will be an issue.