The effective stack depth is 21.5 big blinds. It is a little awkward to resteal all-in after a minraise at that depth (which is one of the reasons it is good to make small raises at that depth, not raises to 3 bb), but that is ok.
I don't understand why you think you had little fold equity since the button would not be getting good odds and should be on a wide range. After he puts in 9% of his stack with something like A2 or K5s, is he going to call off the other 91%?
I think you should be restealing with even weaker hands. Someone who normally raises a 38% range will usually open a wider range on the button, and then there is no calling range that would give 77 trouble. Either you have a lot of equity when called, and you will often be up against only one overcard, or else you have a lot of folding equity.