SF need a good mix of inside and outside skills, but its not like he can get by with mediocre everywhere. In addition, the classification system used by BB might not work as well for for SF.
A forward has to start off with good inside skills, and add a JS. But if a forward has a good IS, he gets classified as a PF. So basically if you have a SF who can also hit from inside, BB says he is too good inside the paint to be a SF.
But if he has a good JS, and less IS, he might have some JR and OD and he gets called a SG. Again BB says he is too good a shooter to be a SF. But its not like being a good shot is such a bad thing.
So I'd look for someone with both good OD and ID, and perhaps is a SG or PF. I doubt that the GE would penalize a SF for having a good IS, perhaps just not utilize it as much; and similarly I don't think there would be a penalty for having a good outside shot. What is the worst than can happen, he takes some 3's and hits them?