What can I use at the top of my stairs for a winch mount?
Having recently moved a refrigerator of about that weight up a set of stairs using only a hand-truck (for wheels) it can be done (I'm not abnormally strong or huge.) Literally take it one step at a time.
If the wheels are not of adequate size to roll on the steps, use a hand-truck with large enough wheels (but not so large you can't stop on a step) and ignore the wheels on the grinder.
But it can be more easily done with two or more people, whether rolling or (when your people can lift it and not be at their limits and at risk of dropping it) brute-force carrying.