You can no longer mount a GoPro to your helmet in AKRA or NKA sanctioned events or tracks that go by these rules . I would suggest a mount that uses rubber pads to absorb as much vibration as possible . I would suggest mounting it on the right side top bar , so it doesn't distract your driver or get in their line of sight .
Some have had great success of taking the top half of a bar mount and using tapping screws or nuts and bolts to secure it to the front fairing. This is on a flat kart though, but I would imagine you could still have success on the front of a champ kart.