If the voting is still open, I cast a vote for leaving it intact as much as possible and repurposing it: if you don’t need a blanket chest, I like Colin’s idea for an entry / mud room storage chest. If these aren’t options, I would choose a project that takes advantage of the size, esp. the width, of the boards. It would seem a shame to have 18″ wide boards and rip them into narrower boards. Your idea of rejoining the boards with dovetails would be fun and ensure the resulting piece would last on for generations. In any case, nice find! Post pics of what you end up with.