Bob- Here are some battery choices I put together. Also, if you do an absorption test, this is how long Ferrari says your charge should last:
<40 ma 25 days
40-60 ma 20 days
60-80 ma 15 days
80-100 ma 10 days
In general, if you drive it once a week and fully charge the battery, you will never have a problem.
your math is a bit incomplete
the " absorbtion test" is the rate of power usage / discharge by the mentioned models. these values are in ma ( mille amperes or 1000ths )
Reserve Capacity of a battery is measured in AH ampere hours, so that an AH of capacity could last weeks ( when used in ma)...( miles per gallon of gas )
typical batteries are considered discharged when at 50% of rated capacity
your battery reference does not have any mention of Reserve Capacity ( the total amount of power available ... gallons or miles per tank of gas ) it only addresses the start capacity cranking amperes / cold cranking amperes, which is the value needed to make use of the absorbtion values.
it used to be that we were only concerned with what it takes to get a motor started ( old school ), today we must also be concerned about the ability to supply power to the various accessories / computers / memories / that need to be kept alive. That value is expressed in the Reserve Capacity. The two capabilites are not dependent on each other. Battery manufacturers are developing batteries which try better to meet both demands. There are hybrid and dual batteries being developed. The dual batteries are like two systems in one, starter is wired to separate terminals, while powered systems are connected to a deep cycle portion.
as has been mentioned, to keep systems powered up and reduce the chance of a battery going flat one needs to compare the reserve capacity to get the best battery for the task.