Evo II: Final Fusillade (Increase Damage by +51. +3 Multishot on last shot in magazine.) We take this because the other perk (Plentiful Mayhem) is absolute dogshit and actively makes the weapon worse.
Evo III: User preference. I prefer +9 magazine size as it allows you to freely spam shots to get back to incarnon mode quickly, but +50% projectile velocity is good too. The other one seems pretty meh, ideally you never even reload with this weapon.
Evo IV: Commodore's Fortune (+20% Crit Chance). We completely neglect status chance on this build because this is a pure viral weapon; viral caps at 10 stacks, and this weapon reaches that cap very quickly even without any bonus status chance.

Fire rate is really, really good; greatly scales the damage output and it's so easy to get back to incarnon there really aren't any ammo concerns. IMO Vile Acceleration is a must-have if you're not getting more fire rate from another source.

[Serration] can be replaced with Galvanized Aptitude (more status chance and higher ceiling, at the cost of making the weapon worse pre-stacks and still dealing less damage overall than [Serration] if you can't get a primer, since this wep applies only 2 statuses)

[Galvanized Scope] can be replaced with [Hammer Shot], [Galvanized Aptitude], [Bladed Rounds], or a Faction mod. Faction mod is best in slot but faction mods are annoying (I usually just use Roar), Scope is 2nd best in slot but you do have to aim down sights and get headshots and stuff which is a bit of a pain (especially since all the giant damage numbers completely block target visibility). If you want the red crit spam Scope is your only option, though. Tbh I mostly went with Serration/Scope cuz I already had 5 V polarities lol, but I think it's still optimal for general use.

Note you're only at a little over 200% crit chance with the basic effect of Scope active, so to get a ton of red crits you're going to want both Vigilante mods on your sentinel and try to get as many headshot kills as possible (for the stacking effect of Scope; each stack is worth just under 20% final crit chance, so at max stacks you can only get red crits). Otherwise it's more of an orange crit monster.

I've tried a viral/heat status focused build and that works pretty well too, but this seems to outperform it. I believe this is due in part to mod slot efficiency; you need to sacrifice 3 slots to get viral/heat as opposed to only 1 slot to get viral.

Also, if you replace [Primed Cryo Rounds] with [High Voltage] (to make Corrosive instead of Viral) and use Nourish to provide your Viral damage, this baby really takes off in kill speed (recommend using [Hammer Shot] over Scope at that point since the status chance becomes more relevant and the conditionals of Scope become more of a pain). It's pretty hilarious, highly recommend you try it.