That kit didn't have a 1" shaft. It was 13/16. It included the shaft, 2 bushings, 2 thin spacers, grease zerk, pin, and a grooved lock plate. The spacer's, pin, bushing's, and grease zerk are all that's available now. You have to make the shaft and lock plate.
Yes you could put in a larger shaft by reaming out the holes but a body would have to be carefull to keep the holes lined up (remembering that any wear in the holes will be on the top side). The only way I would do that is if the holes were severly worn as the 13/16 shaft is plenty strong enough.