The biggest thing that is going to affect the final baking time of a meatloaf (at any temperature) is the size of the loaf itself.
A 3-pound meatloaf is pretty big. This size will take anywhere between 1 hour to 75 minutes (1 hour and 15 minutes).
Meatloaf is pretty versatile when it comes to serving it with accompaniments. My favorite is Roasted Potatoes or mashed seasoned potatoes.