Pretty much spot on. Definitely go with the largest left-handed drill you can. I think they're 1/2-13 bolts...... so if you can perfectly center the "pilot" hole you drill, a 3/8" left handed bit is the ticket.I'd try a left hand drill bit before anything else. Soak it heavily with penetrating oil then center punch in the center. You could use a 1/8 regular drill bit to get a pilot hole than shift to a left had bit (probably a 1/4 " or so).