Drew - I replaced the battery in my SX 2.0 (should be the same size and tray). I bought this guy:

Model# 10-3570-0 GP35/75 / 630 CCA,
6.8 x 8.9 x 8.1" $79.99
It was the biggest I could fit with the stock airbox in place. Even so I had to cut the engine side of the battery tray off - it's a shallow pan style and the battery was about 1/2" wider than the tray so 2mins with the air saw and I was in business.

This one fits too but the 60cca was not worth it to me for double the price:

Model# 10-7590-8 GR75DT-84 / 690 CCA / 80RC $149.99