Patrick, do you know how much base timing the guy had dialed in?
I am in the same boat with the 94 - it is not liking anything less than 91 octane (highest widely avl octane here). hurts the wallet at over 2.50 a gallon.
put a little 87 or 89 in it, run it for a little while, see if there is any detonation. If there is, just dump some premium into her. If not then u're golden. you should be fine with 87 or 89, unless like hissin50 said, u've bumped u're timing a good amount.