FirePig added a post in a topic AMT's Jawbreaker
Thing to do is buid it as you want to build it, from whatever is in the box. Take the instructions (usually required by the rules in most box-stock classes), but also ... take the box.
To really nail it down, take an un-opened Jawbreaker kit along ... if you have one. Any argument with the judges would be quickly dispelled by cracking open a mint, sealed kit.
Speaking from the experience of years of 'head-judging' that would do it for me!
Good luck! Nice model.