Hi there,
Thanks for some extra info. My thoughts...
-there are no guarantees of course!! so everyone you speak with will be offering an opinion...and in some ways, even the admissions decisions are opinions/subjective at the end of the day, and decisions are based on an overall, holistic assessment of you, who you are, what you will bring to the program, how you will use the MBA, how you fit with the school, how you stack up against other applicants, etc.
-given that you've ALREADY established a career in market research and are working towards that trajectory, my view would be there's no reason to make a major shift in directions, even if it is back to what you focused on in undergrad, unless you truly want to change your career direction long term back to that focus.
-if the 750 has been obtained (?), congrats that is a great score, and IF you put together an excellent application, essays, interviews, recommendations, etc I would think you would be considered at Ross.
Good luck on the process! Don't underestimate how important it is to put together a great application and essays, and also to really show why you love Ross!