Statius and Vesta Armors - Would create a better melee set than bandos, which could drop bandos set price for new players and creates a new end game item. Statius is more tanky than Justiciar, unless you are wearing the full Justiciar set, keeping Justiciar sets price high for raids 2 also.
Statius warhammer - Would create a better warhammer than the dwh, which could drop dwh price for new players learning raids 1 and 2.
Vesta's longsword - Would create a closely relatable best in slot spec compared to d claws and ags, which could help bring in more pvp to Indova.
Zuriels armor - Worst than ancestral, therefore keeping the price of ancestral high, which is good for raids 1. Tankier than ancestral but it would create some cheaper items if pvp armors were released.
Morrigan's armor - Slightly tankier and stronger than Armadyl, would drop armadyls price for newer players stuck using d'hides or karils, and creates new end game content.
If this were to be added instead of any custom items, it would keep the real rs feel most of us came here for. It would create new end-game items without being too op, it could be the rewards for the new raids 3, and it would be good content.