When living in Wisconsin, I always made sure my Porsche had plenty of rodent deterrents, after a bad experience the first Winter. Yes block intake and exhaust. But also use rodent traps and poison. I also used a box of mothballs above the engine compartment to discourage rodent ingress.
Equally damaging over long periods of storage is moisture ingress and corrosion inside the heads (some valves will be open when engine is off), and in the fuel tank. So whatever you use on the intake and exhaust sides should also prevent water vapor from condensing inside during inevitable temperature swings. These same temperature swings will also cause H2O condensation inside your fuel tank, proportional to the size of the air space within. So make sure your fuel tank is topped off, ensuring minimal airspace (and "breathing") inside the fuel tank.
This is what I'd do, but I'm an engineer and anal about this topic, after sustaining the damage my Porsche had early on...