I have a hard time imagining Piccolo being less than 80% of Cell Junior. For him to still be standing, this long after the beginning of the fight, it's a hard cell KP. You might think it's a feat, let me tell you something, it's a feat.
How long do you think KKx3 Goku vs Vegeta would have lasted if Goku kept on it? Not very long. And this is ultra durable Vegeta.
Cell Junior fight possibly mimicking something like Reecome vs Vegeta is quite possible. The end of the fight showcasing Piccolo looking sort of how Vegeta looked prior to Reecome about to finish Vegeta off. Vegeta was more worse for wear than Vegeta was though.