Lets talk torque. Its measured in Nm not kg. You mention this thing will be about 1m tall, soto balance or manipulate that long a lever arm there will be a lot of torque needed. What isthe estimated total mass?(Lets assume 500g, 0.9m long, uniformly distributed mass, to hold that out horizontally takesabout 3 Nm, which is a lot. To balance from 10 degrees to the vertical would only be about 0.5 Nmwhich would be within the MG996R's nominal ability. All assuming 500g mass of course. I suspectthe backlash / play in a servo is going to be an issue. Note that stall torque rating for a servo is nota sustainable rating, the servo will overheat and probably melt if held at that torque for a prolonged period.