Only reason Luffy went G5 is cos he likes fighting in G5, he feels free. But Lucci got shitstomped by an ACoC-less G5 Luffy.
G2/3 Luffy with ACoC would've stomped Lucci all the same. ACoC is an even greater power-up then G5 is, especially since Luffy didn't use any mid/high-end G5 attacks (we know that G5's strongest attacks imitate G4's spring mechanism).
Lucci is mid YC1 at best, below King and around Marco/Katakuri.