Another 612 battery question

I know that the 612 takes a 34R AGM battery which is getting more and more difficult to find in stock. Batteries seemed to have doubled in price over the past few years and maybe I am just being cheap but I'm not looking to spend close to $500 (all in with sales tax) on the 34R Interstate Battery. Costco carries Interstate batteries but not the 34R.

The 34R batteries generally have in the range of 800 -850 CCA. I live in California so not extreme cold for high powered starting and not extreme heat that often in my area. The H6 AGM Interstate battery is basically the same physical size, has the correct terminal position and has 760 CCA. Is the car going to notice the difference of those 40 CCA's? I keep her on my CTEK tender in the garage so we should always be at a full charge.

 

The last battery in the car was a Red Top. Probably had it 6+ years and never an issue. (Also had one in my 355 that lasted more than 6 years until I ran it down leaving the key on in the ignition for a week.) The tender showed the battery fully charged as I unhooked it to make a 2 mile trip to the gas station for a fill up. At the station, I went to start up and NOTHING. The dash flashed 2 times and then went blank. I knew it couldn't be the battery as it just had a full charge on my CTEK.

Eventually I opened up the trunk and checked the battery. The negative post on the battery had come right off. No idea what would have caused that. No big bumps or pot holes on the trip. I'm thinking that it must have happened sometime earlier and was just sitting there still making contact. Never seen a terminal post sheer off.

 

That's what brings me to an H6. The 612 has a tight battery compartment. The H6 has the right terminals and battery size. The CCA was slightly lower at 760.