U probably have group 27 batteries. The cig battery box will fit up to a group 31.
Try to get 800 amp cc / 1000 mca starting batteries. If you go with a flooded battery, interstate makes a decent marine starting battery (27M-Xhd) . If you want the best, get an Odyssey agm battery (31M- PC2150), but be ready to spend $300+ per side.