I don't think improving the GMAT score from 720 to 750 would make a difference. 720 is a great score, I don't see why this would be a concern.
Your profile seems very strong to me. Great GMAT, great coursework, research and teaching experience in relevant topics, letters from accomplished professors. Seems to the ticking all the boxes.
I'm not in Accounting to have a reliable opinion about accounting classes, but I also think that looks ok. Of course, it will depend a little on your research topics.
One thing that I have not seen clearly explained is why Accounting, instead of Finance or Economics (after all, those would also be possibilities). But I guess you will provide a good answer for that in your SoP.
You seem to be dreaming big (as you should), but still applying to a wide range (as you should). So, I really think it looks good.