Looks like your calculations are correct. However, I recommend at this kind of stack size, 20bb or so, you start thinking about things in terms of 3bet-call/3bet-fold/call/shove/fold being your 5 different options. Shoving and calling are definitely options here with certain hands, and you need to figure out which is the most profitable.

In this particular spot, it seems like villain is shoving with such a small portion of his opening range that this would be a very profitable 3bet/fold. However, with a stronger hand than K9s, you're right that we would not be able to 3bet/fold because we would be priced in to call, so we should consider another, potentially more profitable line – perhaps shoving, perhaps calling, perhaps folding.

Your thought processes are a little backwards. I'm not sure why you would want to start 3betting stronger hands than K9s and forcing yourself to call it off – if anything, it means that you can afford to 3bet weaker hands than K9s and still comfortably fold. As with many spots, I think this looks like a good spot to 3bet/call the top of your range, fold or 3bet/fold the bottom, and shove the middle parts, the hands like 44 or KJs that are profitable shoves but less than ideal as a 3bet/call. Depending on the circumstances, K9s might fall into this category too.