Use Mattermark.com to find them. They have a 14 days free trial. The tool will let you filter by founding and type of company, so it will probably give you what you need.
Talk to market first simply dialing and smiling. Can also outsource for someone to call and set appointments for you to speak with them. Have found good affordable people on Elance.
Recently launched Subleger http://subledger.com/ is trying to do some or all of what you describe. It doesn't mean that there isn't room for others but consider that many early-stage companies don't have complex revenue in-flow so the core of what you're describing (converting or merging income ...