Results Driven SEO Needed - Long Term Work

Hi there, We run some large websites, and run our SEO in house. We are looking to take our SEO to the next level, and want to work with someone to take our rankings even higher then what they are currently. We are looking to work with someone on a results ONLY arrangement, where we would stipulate our keywords, and then you as the provider would do what is needed to get us to the number 1 position. Once rankings are achieved and stable for an agreed time frame, then we would pay for that particular keyword. We await your messages, I also want to add that we are looking for a longterm relationship here.