I thought gambling was ilvl + / - 5 of your clvl...? Am I mistaken? Going from what you said, a clvl 67 character could, potentially, gamble a BStar? :fortuneteller:
Your character needs to +5/-4 within the qlvl of the item your gambling to successfully gamble it.So in the case of qlvl 70 baranars you would need to be at least lvl 66.
This link may help you http://www.battle.net/diablo2exp/basics/gambling.shtml