There is lots of choice of 7" LED units out there and I'm afraid I couldn't recommend or deride any of them as I have not tried any out.
However I can tell you that if you would like to retain your original Monster headlamp shell and rim, then I can help you with an adapter that will enable you to fit any 7" lamp unit of your choice.
Details here, but please let me quote you for mail if you are in fact in New Zealand!
http://www.ukmonster.co.uk/monster/s...adlamp+adapter
You might be able to glean some info on LEDs here too..
http://www.ukmonster.co.uk/monster/s...adlamp+adapter