Narukami

Grade 0 = 17
Lizard Soldier, Saishin
4 Demonic Dragon Nymph, Seiobo
4 Malevolent Djinn
4 Old Dragon Mage
4 Yellow Gem Carbuncle

Grade 1 - 13
4 Wyvern Guard Guld
4 Red River Dragoon
3 Photon Bomber Wyvern
2 Lightning of Hope, Helena

Grade 2 - 13
3 Demonic Dragon Berserker, Garuda
2 Dragonic Deathscythe
4 Thunder Storm Dragoon
4 Hex Cannon Wyvern

Grade 3 - 7
3 Dragonic Kasier Vermillion
4 Thunder Break Dragon

You don't need to max Photon Bomber. Run 2-3.
You don't need the Desert Gunners... though people use them a lot these days.
You don't need Shield-Blade.
You don't need G3 Djinn.

Max Thunder Break.
Put Garuda at 3-4.
Run Hex Cannon Wyvern.

The grade 1 Gunners are adequate boosters at 7k, but the g2 Gunners are bad.

The changes you made already are pretty solid, though. As a personal thing, I don't really like Deathscythe anymore, since your main retiring point goes to TBD/Vermillion, but it's better than a fair number of other choices.