I think you are pursuing the wrong path.
Buy (or 3d print) some gears for your servo.
Make them of the ratio 3:2 or there abouts.
Big one on your servo. Little on on your object to be turned.
270 degrees of movement! 
I think you are pursuing the wrong path.
Buy (or 3d print) some gears for your servo.
Make them of the ratio 3:2 or there abouts.
Big one on your servo. Little on on your object to be turned.
270 degrees of movement!