UMass interviews >50% of instate applicants so that would be your best shot, but unfortunately it's MA's only public institution. 58% translates to about an 8, and 506 translates to about a 29. Since UMass has an MCAT median of 33 with a 10% at 29, I would DEFINITELY recommend applying to DO schools as well lower tier MD schools. If you want to be a doctor it shouldn't matter if its an MD or DO by the name.
I hope you included these schools in your application:
New York Medical
For some of these schools you have a better chance for an interview than others. If you are unwilling to apply to DO schools then also include California Northstate. If no success with MD schools this year then apply to at least 10 DO schools next year.