Stair repair. How’s my plan?

Never worked with concrete before in my life, but I’ve got some pretty bad stairs I want to try to repair. My plan is to fill in the large voids with Portland cement, med grain sand, and “concrete bonding adhesive acrylic fortifier”. For finishing the vertical surface, I have a tub of quikrete polymer modified structural repair. Will this do the trick? Should I worry about the fact that the stairs have dropped about an inch from when it was poured (see pic)?