I'm not a real fan of absolute hereditary monarchy, but believe that there should be a Constitutional Catholic Monarch (Autocracy) where the Church maintained checks and balances, veto power over all legislation, as well as veto candidates who are unsuitable, etc. Because it's absolute, there's nothing to prevent a wicked monarch like Henry VIII from taking an entire country into apostasy. Because it's hereditary, you're not necessarily getting the best and most competent men. There could be an election from a group of men who are screened by the Church, and then of course only men would vote, with men having as many "votes" as are members of his family. There would be a reasonable term limit, say, 8 to 10 years, but the candidate could run again.