Engine rating selection

Does anyone know how I can change models from one engine variant to another, or is it even possible. For example, if I fly the Alaska 739 with 26K and I want to fly the KLM 739 with 27K. I know you can change the panel style in the PMDG menu, but I have not come across any with the 27K engine. Does selecting a style also change the engine type to match that airline? Also, does 1K extra on the engine make that much of a performance difference (in the sim), such as with the flight dynamics?