How do I respectfully address someone in Spanish if I don’t know their last name?

I recently met a neighbor who speaks Spanish and very little English. He’s a very nice older guy, probably around my grandparents’ age. He told me his first name, but not his last. How would I respectfully address him not knowing his last name? Would “Señor _name_” work, or is there another title I should use?

submitted by /u/TheBas_043
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