Leves are affected by armoury bonus, I'm sure. Also, you can't "pre-do" battle leves because if you hand them in on another job you will still get the exp on the job you did them as. For example, I don't think you can do a leve as a 50 bard and turn it in as a 45 summoner and get the exp for summoner (not talking challenge exp). So it'd probably work for the currently available jobs but not for machinist because you'd just get the xp for the job you did them as.