Not familar with the ejector on the Mossberg, but on the Contenders the ejector can be modified to work with the new catridge easily.
Could make yours a 22-250. Had a 223 Contender rechambered to 225 Winchester, but was too much for the action as brass stuck easily.
If you wanted to spend the money for a rebore job any of the TCU cartridges work well as rifles. There is an article in one of the recent gun magazines on a 7 TCU rifle. These use 223 as parent brass.