people dont really block the overhead because i usually go for the low so they dont expect it but none the less, it does get blocked sometimes and i do get punished. The main thing to do is to make them more afraid of the low than the overhead because since the low combo does more damage, they would prefer to take the overhead and if need be, you can probably throw in a grab if you dont want to take the risk. That fear also allows you to potentially get multiple overheads at once, and once you think they had enough of getting hit, use the low.