Villain is a winning player who understands concepts of pot odds, board textures, odds, etc. I've seen make bluffs on scare cards and pot control with more marginal hands. We're playing 200NL $1/$2 blinds with a $200 max buy-in. This was live game, so there isn't a hand history converter. Please bear with me. Here's the action: 

Folds around and I'm dealt 99 in LP and open for $16 which has been the standard for the night. The dealer calls and Villain in the BB calls as well. Effective stacks are around $250. 

Flop: K94cc. 

Villain checks, I bet $24 (in retrospect, I should've sized a bit larger), and Villain calls. 

Turn: 6c. 

Villain checks, I bet $44. Villain calls. At this point, Villain could have a variety of Kx and small flushes. 

River: 2c, completing the four flush.

Villain donk bets for $50. I raise $150. In this spot, I think Villain has a capped range, since he would make a significantly larger bet with a stronger hand. Having called out of the SB, I doubt he has many strong clubs in his range and his donk bet probably is a blocker bet. Because I can have larger clubs in my hand, I think this is a profitable spot to bluff raise. Villain's range is capped and he is capable of folding. We're risking $150 to win $256, so our bluff only has to work 36.95%. Thoughts?