76s vs. OMC. Should I bluff 3 barrels?

5/5

~$500 effective

SB - OMC. His hands were shaking during the hand, and he looked nervous.

OTR he checked very quickly.

Hero(CO) 7♥6♥ opens to $20, SB calls

Flop($45) Q♦ 8♠ 4♠

SB checks, Hero bets $20, SB calls

Turn($85) A♥

SB checks, Hero bets $60, SB calls

River($205) 9♥

SB checks, Hero - ?