EVER DO SOMETHING you regret instantly? How did you manage to get over it? James Zeivel, now of Glendale, Arizona, went through all that back in 1969, while living in Chicago. He traded in his beloved 1966 Pontiac GTO convertible — purchased new from People’s Pontiac on his return from Vietnam — for a 1969 Dodge Charger. It looked like an improvement on paper, but…. “The day I picked up the Charger and drove it,” he recalls, “I knew I had made a mistake.” Worse yet, “There was nothing I could do, the damage was done.” The ’66 was gone, but never forgotten. In fact, he eventually tracked it down, in 1985, and spent four years restoring it. Now the ’66 and this ’70 are stablemates, “and always will be.”…