osterizer

Generally about a 2100mAh 3S pack will work, since they're mostly a similar size, but you should look at the physical measurements of a pack you're considering to be sure the new one will physically fit. A 20C pack will be sufficient, but higher current specs won't hurt anything.

Increasing the capacity may get you moderately longer flights, but likely not much, and larger packs may have difficulty fitting in the frame. You still need to be careful of the dimensions.