meh, reading maniacs is hard. If you have his range as, say, a few better Kx hands, T9, and 87, you're flipping. Take out the better K's and you're 60/40 - but that assumes he doesn't have a better hand (2pr, set, oesd).
When you decide to 3bet, you should already be planning to either shove or fold over a 4bet. If you're not confident in your read that you're ahead of his range and will have to fold to a 4bet oop, don't 3bet - but I wouldn't be crazy about calling oop with TPNK either.
70% of your stack is committed? Snap shove as played.