Interesting thread. I took all the things that you wrote into consideration, but I still do not see Naruto being close to defeating Hashirama.
Hashirama's jutsu seem to be geared towards suppressing and defeating bijuu. His mokuton abilities include techniques specifically used to counter bijuu skills, such as a wooden dragon that absorbs their chakra, and a wooden golem that can catch and return a bijuudama. These two moves alone hamper the overtly destructive aspects of Naruto's fighting style. If Naruto chose to engage Hashirama in his beast mode cloak form, I am sure that Hashirama would be able to defeat him.
In his human, cloaked form, Naruto's techniques are limited to his speed, his clones, partial transformations, and his rasengan (and their variations.) On the other hand, Hashirama has his wood release, his weapons, and strength that is above Madara's physically. And in terms of tactics, Naruto is very good at creating plans on the spur of the moment, but Hashirama is a seasoned veteran that lead a clan to the height of the ninja world. He has been on the battlefield longer, and had a rival like Madara to constantly push the limits of his mental and physical endurance. His battle oriented maturity will help him defeat Naruto. I am sure that Naruto would not even know that the flowers are releasing a pollen into the air. None of the other kage did. And Hashirama does not appear to be a target that would lose in a chakra using battle. He has better control, stronger chakra in general, and possibly more in general.
In conclusion, I think that Hashirama would defeat Naruto, and it would not be especially challenging.