I don't think you will be happy with 1 inch castors, for one thing they are rated for about 30 pounds ;, also the contact area with the floor is so small they will slide even when locked. What would be ideal, but that I havn't seen in ages, is the type they used to use on typewriter tables, they have a lever that extends them down to roll the table, then you retract them letting the table stand on it's own (stronger) feet in use.
Or you could put 2 castors on one side just above floor level, and tilt it like a 2 wheel cart to move it around...(insertable pipe handle with pin...)
2c