To add any Mythic you'd want to use - Simply wear the mythic and move whatever set you removed to your shoulder slot, then equip a Slimecraw helm. (or Kra'ghs if you need pen instead)
Order's Wrath can be replaced with a trial set like Ansuuls whenever you get it. Many options are available for this.
Harpooners Kilt is bad in dungeons, do not use it there.
Remember to check passives to make sure you have all what you need.
Important DPS notes
Start using JESUS BEAM at 40% hp instead of jabs.
Drink your potion every time its available for the buffs.
Replace Solar barrage with Restoring Focus for added Resists, Healing and Stamina Recovery if needed/wanted. If you need more healing you can use Resolving Vigor.
If you're solo and need breach, replace Solar Barrage with Razor Caltrops