Initially in the printer’s manuscript, Hyrum Smith wrote “ye could have just men to be your judges”, which he immediately corrected by crossing out judges and writing inline the correct kings. Here Hyrum seems to have been influenced by the preceding use of judges in verse 11, especially the phrase “wise men to be judges”:
In this chapter, king Mosiah is arguing for replacing kings with judges, so clearly kings is correct.
Summary: Maintain in Mosiah 29:13 the corrected reading in 𝓟: “if it were possible that ye could have just men to be your kings”.