Best thing a friend did was put steel casters under his safe, if he needs to move it he lays down plywood to protect the floor, muscles it up onto it(he cuts an edge at a slope to help), then rolls it to a different room. Any stairs he rents an appliance hand truck that is battery operated and has "feet" that walk it down stairs. Make sure the feet are solid and not sloppy, and any rubber tread is in good shape, if it is smooth they can slip!
https://youtu.be/ifWSXhCJFkE?feature=shared&t=77