If you haven't already try the Odyssey line. Enersys, who makes batteries to military specs will serve very well for cranking but also amp hour. To give you an idea, the group 31 is used in our military M1 tanks .

Best of luck

 

.....just put the DieHard AGMG Gp49 Main (left) battery in my 10Speed...fits exactly and works great...And cost $170 on sale online JimB

 

I have to keep a trickle changer on the "hotel" battery in my 2000 Arnage Red Label. I keep getting the "Service Battery" alarm even when I got new interstate batteries.