More calculations--
The chance of airloads destroying a servo -are about zero.
The chance of calculating the load -then finding a servo which actually meets that criteria - less than zero.
The chance of poor geometry wrecking the real work availble from the servo- about 99.99%
The chance of improper power supply affecting the output of the servo - about 75%.
The servo selected is important -but far less important than understanding the correct linkage and proper servo power supply
But read the calcs- THEN find out how servos really operate and what the linkage can affect.
In most cases, a less powerful servo (rated at less torque) will do the job.
The new digital servos provide much more control about neutral ( some call it holding power) and a low torque digital can oft do a much better job than a higher rated (more torque) servo.
If you don't understand why - then servo selection is just a blind guess.