The Vedas say that Brahma lives in the Sun. Some commentators have said that Brahma is for this solar system only as he resides in the Sun. If there is life on other systems outside our own, they would have their own Brahmas. If you accept this, then the age of 1 day of Brahma maps pretty good to the lifetime of the Sun.
Sankaracharya has also said that these stories do not have to be taken literally as true. They can be taken as parables. They were done in this manner to make a complex situation understandable to ignorant people.
Reagrdless as to which story you think is better, all point to Brahman as the sole cause of this universe. All point to Brahman being the only true Reality. Realize God and ask Him directly what is true. Arguing over which story is true is pointless, it is the same as arguing over the husk and letting the rice be gone. As Ramakrishna Paramahamsa said, we are here to enjoy mangoes, not to count how many leaves are on each mange tree....
You should be a little less hesitant to accept science as absolute. What science was saying 200 years ago is different from what science was saying 100 years ago is different from what science says today and will be different from what science will be saying in 100 years. Less that 100 years ago it was still generally accepted that there was only 1 galaxy. I saw on the internet last week a new paper by some astrophysicists that says there was no big bang; the universe is expanding in both directions (past and future)...