The demihuman classes in Labyrinth Lord list average height and weight (which I threw out for my elves to make them more statuesque, and hardly matter for halflings in exile or dwarves in extinction). Size guidelines for humans are a touch more obscure.

My initial plan was to just provide a paragraph or two of human default information. But the more I think about providing custom ranges for the human classes (cleric, fighter, magic-user, thief), the more excited I get.

I’m setting average height for male humans at 165cm (5’5″), and average weight at 150 pounds. (Less three inches for women, but not less any weight). Well, that’s what I’m setting for clerics and fighters. For magic users and thieves, I’m setting it at 5’4 and 130 pounds.
I’m not limiting top or bottom ends of PCs, but for NPCs, I’ll probably be using ye-olde “sixty inches plus 1d10 or 1d6)”.