Permit dates prior to 1970s?

So, I’m adding various historical documents to a WordPress instance. The documents go back to the mid-1700s, and I’d like to use WordPress’s dates to organize them, but it doesn’t look like the dates can be set earlier than sometime in the 1970s.

I know I could use custom fields for some of this, but that wouldn’t let me use the dates for permalinks, categories, and calendar archive views.

Suggestions?