Go to your "local" CIH dealer. It may or may not still be available.
That is a very special bearing that IH used when they changed from a bronze bushing in the pitman to the ball bearing. IIRC the ball bearing was an option when first introduced. They apparently did it this way so they could use the same crank pin for both the bushing and the bearing.
If you can match up everything wut the width of the inner race, you could have some spacers machined to take up the space.