One of the most valuable skills for any cook is an ability to adapt on the fly if the ingredients you have on hand aren't what the recipe calls for. That can be easy or difficult, depending on the situation. For example, replacing eggs in baking is a significant challenge, but substituting one piece of meat for another is usually straightforward. If your recipe calls for a boneless pork loin, it's easy to prepare a bone-in loin instead.
Bone Out, Bone In
The pork loin is a relatively long muscle, running along the animal's backbone from its neck to its hindquarters. It's a very tender muscle because its primary job is just to support the spine. The pork loin you find at the butcher's shop is cut from the back half of the loin muscle. The butcher cuts away the thick "chine" bone at the bottom, leaving short rib bones down one side of the roast. Cook the bone-in loin as you would with a boneless loin, cooking it to a minimum internal temperature of 145 degrees Fahrenheit. Bone-in roasts might need slightly less cooking time.