For this recipe I use a combination of ground chuck (80/20) and ground pork. If you prefer to use one or the other, that’s fine.
The chicken livers are an essential part of Dirty Rice. Many recipes call for using the gizzards also, so that is certainly an option. Don’t go overboard on the livers because they can certainly take over the flavor profile. They should be a subtle background flavor, like all the other ingredients.
Remember that most commercial creole seasonings and commercial stocks have high salt content, so make sure that you taste as you cook before you add any more salt.