yes but the juubi is stronger then those combined.. why would kurama say it is immeasurable? secondly, the bijuu sage mode only adds 33% chakrawise.... so CHAKRAWISE the juubi's jin would be stronger.
And then again, Obito's Juubi isn't even complete. The fruit hasn't formed. Naruto doesn't have the full Kurama. We don't even know the proportion of power of each bijuu.
You are assuming way too much things... your statements are not conclusive.
I even could reference the Kurama on its weakest possible situation (sharing chakra with all SA) almost completely blocked Tenpenchii (this technique was executed by 1-7 tails + partial 8-9 tails). The cloak was anything but dense at that point, and still Naruto was able to save the alliance from one of the most powerful skills of the Juubi. Doesn't this tell you that Yang Kurama was understimating itself? Only half of kurama is incredibly strong, I still wonder what would do the Full Kurama.
So, I gave you the proof that only Half of Kurama was enough to fight the first stage of the Juubi, on its "unmeasurable state". And I told you about Naruto combining this power with Sage Mode.
How can you be so certain about him being weaker than Obito? Is there any explicit proof that concludes in absolute terms, that Bijuu Mode Naruto can't fight against Imperfect Jinchuuriki Obito?