New B2B product ideia and two companies

I have an idea for a product that involves two companies. This will be a new B2B product and of course it needs to be validated as a new product in a joint venture.

A company A already has a similar product that with few developments can become the new product. The company B has the business knowledge that would help the new product and I know that was a product that they were looking for in the past.

What should be my approach to both companies? Company A approached me to be a project manager for them and this could be my first pitch.
What do you think should be the economics between both companies of this type of business?

What advice do you have for me as lead head on this project?

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