If you’re planning to help that evening, you’ll be on Viper since that’s your current raid job and you have it BIS. You’re most familiar with that job out of all of them. For savage raiding, everyone needs to be on a different job, so make sure everyone picks something unique.
The DPS roles should be split into 1 caster, 1 physical ranged, and 2 melee. Savage raids are designed to be played with specific setups, and having the DPS split this way will give the entire team a boost.
For healers, I recommend having 1 shield healer (either Sage or Scholar) and 1 pure healer (either Astro or Whitemage). This combination will provide a balanced healing approach.