No guarantees, per se, but some have linkage programs. Search SDN under postbac linkage and you'll get tons of info. Tufts, Bryn Mawr, Goucher are some that I can think of that have linkages. The special masters programs also have agreements of guaranteed interviews with the right GPA/MCAT combo.
As far as numbers, again this varies school to school and also by type of program (masters vs. undergrad courses). Hard and fast rule-- around a 3.0-3.3 GPA and a 27 MCAT for some of the more competitive programs, though your mileage may vary. Many get into programs with much less than a 3.0 or 27. Best of luck 👍