LF large breed female dog

Looking for large breed (~90+ lb) female dog.
Can be mixed.
Must be good with cats and other dogs.
Prefer under 2 years old.
Have local vet so spay and shot status aren't as important, but information regarding these would be welcome (will get her up-to-date).
Must be calm temperament.
Non-aggressive, non-food-aggressive.
Have ~1.
6 acres of land and partially fenced yard, plan to expand fenced portion.
Dog would be indoor with access to yard.
Large house so plenty of room.
Currently have an older female cat.
Have some gear and supplies already.
She will be spoiled, but she will also hopefully be trained for assistance service.