I would do this as a Chrome extension, something like https://getnewsbot.com but geared more towards a historical context (vs. similarity)
Are you planning on writing all these articles yourself?
I hope you realize you need a pretty large team to run a news website.
I would start with a skeleton crew, including volunteer contributors, and scale over time as readership increases.
Maybe you should start with one good such article and see if it takes off. I think you're severely underestimating the amount of work needed, and severely overestimating the demand.