Some guitarists prefer to have the 81 in the neck position for more sustain and power during lead playing, while using the 85 in the bridge for a more balanced and controlled rhythm tone. This setup provides the best of both worlds, allowing for both aggressive leads and clear, punchy rhythm playing.
However, if you prioritize power and aggression over versatility, then having the 81 in the bridge position might be a better option. This will give you maximum output and sustain for lead playing, while the 85 in the neck position will still provide enough warmth for rhythm playing.
Ultimately, the decision should be based on your own playing style and musical preferences. Experiment with both setups and see what works best for you. You may even find that you prefer a different combination of EMG pickups altogether.