To get biscuits that high she must roll them out thick, like about 1". I roll mine about 3/4" and mine are a good 2" high.
This will make some people cringe, but I get the best biscuits when I use lard for shortening. I also add an extra 1/2 tsp. baking powder. I do not over mix and add as little wet ingredient as possible. When I turn them out if dough is dry I sprinkle with water and knead in just enough so dough can be rolled. Shortening should be cold, just like pie crust. I cut large biscuits (grand size). I just use an ordinary baking powder biscuit recipe.
I really like buttermilk biscuits but haven't found the secret of making good ones.