I have no experience of your situation but I think you should perhaps start by negotiating your level and title as an employee as part of the acquisition. I suppose that what's achievable is correlated to the size of your startup.
Whether you join as, say, Director or VP will have a direct consequential impact on your salary (you'll automatically fall within different compensation bands) but also on your standing within the company.
Whether you join as, say, Director or VP will have a direct consequential impact on your salary (you'll automatically fall within different compensation bands) but also on your standing within the company.