Put it as low as you can, but be certain it is high enough to allow space for the seals AND the bazooka. The simplest way to do this is place the bazooka in the kettle & mark the side, then do the same with the seal. Drill the higher spot.
You'll most likely put some type of siphon tube in your kettle so you don't have to worry that it might be up a little high. Better too high than too low.