I would get the largest battery (cold cranking amps) that will fit. From what I have been told there are only a few battery manufacturers that everybody buys from and has them labeled. I have a 950 CCA 60 month in my car. Also make sure your alternator belt is tight. A loose belt can result in a lower charge rate. I had similar problems to yours with a new battery.

1)Pull and clean plug on top of alternator
2) Tighten belt
3) With car running you should get about 14V across the battery.

Auto zone will test your battery for you right out in the parking lot. They are sometimes confused as thier tester does not have a setting for 5 cylinders!