Interesting thread. I assume that raising with an 8/set/TP doesn't happen at your level, so it's at least a K. KQ/KK would definitely bet the flop, so AK is most probable. Although it's always possible that he read you like a book and/or thought you couldn't call this with your small stack and it was a bluff with 77/66 Notice he could still fold to a reraise AI with this 300-raise..

Would you bet the flop if you had a bigger stack (>1000-1500)?.