Sail servos geenrally have more torque. I think many standard servos are about 3kg/cm torque.
Sail arm servos can be between 7kg/cm and 25kg/cm
There are sail arm servos and sail winch servos.
Most sail arm servos only have 90degrees of movement, some have 140 deg. Howver all servos can be modifed to give more turn.
I am not sparky, so I could not tell you how it is done, but there are otehr thread on this form. Give it a couple of hours and you will have more answers on how, if you want.
Sail winch servos have a a drum that turns up to about 3.5 turns. Bigger drum means more line pulled in.
But if you are using a sail arm, you can pull more cable by haveing a longer servo arm attached.
Looking at your picks 90degrees is plenty. and I doubt you would need the extra torque of a sail arm servo.
If you do a sketch of how you plan to open/close the ramp it would help. Are you thinking of running a cable system, directyl attach servo to ramp, or what?