6) Tune "Fire Ant" with the Level 5 "Quilla" and Synchro Summon "Sun Dragon Inti".
"Limit Reverse": This trap allows you to Special Summon a monster with 1000 attack or less. "Oracle", "Fire Ant" and "Supay" all have under 1000 attack, so this card can be used to revive the monsters and use them for more Synchro Monsters.
"Skill Drain": This card shuts down all monster effects for the cost of 1000 life points. This card counters many decks in the current meta. Also, the Dragon's effect activates in the Graveyard, so it will not burden the deck.
"Scrap-Iron Scarecrow" because many level 5 monsters need the field open for special summon, so you will need to use trap and spells to block attacks.
Whilst Inca can be a formidable deck, there are many cards that may cause huge problems for Inca. The main problem is cards that banish the Dragons, or return them back to the extra Deck. For example, cards like "Bottomless Trap Hole" and "D.D. Crow" are able to permanently remove the dragons from the game, thus ending the loop. While "Brionac, Dragon of the Ice Barrier" could return them to the extra Deck, which means you will have to re-Synchro Summon the Dragons. Use "Imperial Iron Wall" to prevent the loop from stopping.
"Solemn Judgment" and "Solemn Warning" prevent the Dragons from being summoned and therefore, the loop is delayed. Use "Seven Tools of the Bandit" and "Dark Bribe" to negate these.
Another weakness is that the Dragons both require specific Tuner monsters.
Inti and Quilla are most likely paired up and given the ability to revive one another because Inti, the sun god, was married to Mama Quilla, the moon goddess. "Earthbound Immortal Wiraqocha Rasca" is also based on Viraqocha, the god of everything in Incan culture.