I can only relate the amount to stuff relative to what I commonly used... For instance on my 58" airplanes... they commonly recommended a servo that has around 42 oz-in of torque .... but as to what that actually means in pulling power, I didn't need to learn that... I just needed to know it fit the recommended specs for the airplane I was putting together. I didn't need to know how much pull it had, just that it was enough for my needs.
The only way I know to find out if something is enough or not... is through experimentation. I'm certainly not sure if the rotational torque is direct or otherwise proportional to linear pull or not. So testing is in order. Measure how much force you need to pull on whatever you need pulled using a force gauge... then test to see if the servo is able to provide that by again, measuring that amount using a force gauge. I'd assume you can convert between oz's and lbs by dividing by 16 ( or multiply if going the other direction )... if you need to convert it further.