Start off by NOT building any of the fancy infrastructure—the crawler, crunchbase joiner, LDA algorithm to cluster investors, etc.
But set up a form where somebody can enter their company idea, URL, and traction metrics and then you'll do the research and suggest 5-10 VC firms and partners.
You (the maker of the site) will learn a lot from being the wizard of oz behind the curtain.
And when you're done, you have two routes: 1) the "Google" approach: build algorithms to automate what you're doing already, 2) the "eBay" approach: let the VCs themselves onto the site, show them a stream of (anonymized?) pitches, and let them choose which entrepreneurs to meet. No need for an algorithm. Then the site becomes a marketplace to match startups and investors, a sort of an online, always-running demo day.