Kami was unable to track the fight, but considering the Ginyus were also unable to track Goku's movements when this latter was using a battle power of around 60k, I don't think it necessarily denotes a gap bigger than that (i.e, bigger than a 60/100 ratio).
But I'd still go with a 40/100 ~ 50/100 ratio or so, considering Piccolo had already stated he was considerably above Kami-Sama by stating Goku is far more of a threat than Kami, who had slacked off. So, by that comment, Piccolo being >> Kami-sama was already made clear, yet the Z warriors seemed rather surprised with the prospect of the initial scuffle between Goku and Piccolo being just their warm up, which all in all would imply that the initial level they were using is already enough to swiftly outclass Kami-Sama, I'd say.
Kami-Sama : 40
Piccolo/Goku (initially) : 60
Piccolo/Goku (full power) : 80 ~ 100
There's also Goku, upon giving Piccolo the freebie to punch him, stating Piccolo's punches aren't half what it used to be. Whilst you could argue the "half" was just a hyperbole, it should at least imply Piccolo has weakened considerably by then. And then, even upon wasting a lot of energy using the Bakurikki Maha, to which Goku could swiftly outclass him to the point Piccolo couldn't even defend himself and even after weakening himself considerably even more than that (after suffering that beatdown by Goku's hands), it's suggested Piccolo is still on a different tier from Kami, as Kami would rather order Tenshinhan to kill himself than to attempt anything against Piccolo.
Piccolo (full power) >> Piccolo ("punches aren't the same they used to be") >> Piccolo (post special attack) >> Piccolo (post Goku's beatdown) >> Kami-Sama
So, no matter how you slice it, the gap is huge, and I think even a Goku-Ginyu gap isn't doing justice here due to all those "breakdown powers". A 40/100 gap works fine here to me so I can fit all those suggested weakened powers more smoothly.
