Did you see a type of actuator that might be of interest? You can get low rpm from a servo motor and properly programmed servo controller. You indicate “high torque” but can you provide a value? Torque = Force x Distance (for example if you are raising a 10 ounce load at a distance of 5 inches from the pivot point, you would need 10x5=50oz-in). If you are not sure, can you provide a simple diagram with dimensions and weights?