Group 65 is correct and 675 CCA sufficient; don't know about the C-15
Go to retailmenot and get a coupon code for Advance auto, usually you can get 40% off and check their prices; order online and P/U at a local store. Look at getting the Gold rather then the Silver, usually the additional discount makes the price close. Don't pay extra for the additional warranty.
the codes almost always work for me. Use the code that saves you the most
wd5 code is good for $50 off $125, The Group 65 Silver is $126.99; take off $50 = $76.99