Lectric Limited (
www.lectriclimited.com) manufactures the correct "spring-ring" battery cables sold by all the Camaro parts vendors.
The R-59 battery was also used in the '67 Corvette, and several types of that battery are manufactured and sold by Restoration Battery,
www.restorationbattery.com; they have maintenance-free versions now, and can date them to meet your needs.
Personally, I use Delco Professional Series #24-7YR batteries in my '69 Z/28 and '67 Corvette; I just replaced the one in my Z/28 after 12 years, and the one in my Corvette is 11 years old and still going strong.