SAN JOSE, Calif. — It turns out headhunting in early San Francisco really did involve hunting and noggins, though in quite unpleasant terms. Captains needing sailors had runners lure men to saloons with promises of free liquor and fun women. Instead, they’d get whiskey laced with opium. “After he drank it, he’d get woozy, and that’s when the bartender would whip out a little leather-covered club and hit him over the head, pull a lever, and drop him down onto a mattress in the basement,” says Daniel Bacon. “He’d be held there for a short period, until he was put on a ship, and once that ship sa…