yes, h6 will fit, but i would not recommend optima. i have 2 redtops just gathering dust right now after only a year of service, despite regular topups and plenty of driving.
i would go with Deka, or Napa, or Odyssey. If you are shelling out the $$$, Odyssey is really the way to go. They make a 34 size battery in the Extreme Performance lineup that will fit perfectly.