There are some things that require the use of faith, and other things that are simply history. Even if they found the ark, that would not make people exercise their faith and get saved. All it would do is show more evidence that the accounts of historical events in the Hebrew Bible actually happened.
“Even if they found the ark, that would not make people exercise their faith and get saved.”
“...An evil and adulterous generation seeketh after a sign; and there shall no sign be given to it, but the sign of the prophet Jonas:
For as Jonas was three days and three nights in the whale’s belly; so shall the Son of man be three days and three nights in the heart of the earth.” Matt. 12:39-40
They wanted a sign too, and they were given one, and it didn’t make everyone repent. So I think you’re right, a lesser sign given today probably won’t help much.