Okay, a brief look over and I have an 'alternative' idea.
I see the valve that controls the air in the drag link as the heart of this system. That "link" has mechanical stops (inside) to give the part full strength by the arm-strong method (as if no compressed air is present). Inside, it is a valve that has a plunger acting against a spring (both forward and back). And the airflow is large enough to handle full flow...making it a larger "valve".
I build high security jail locks using pneumatics, most of which are pilot controlled internally in the valves. It occurred to me to put the larger valve closer to the cylinder and use pilot lines to control the valve. The link valve then, would have a piston actuator (both directions) and only use pilot line flow, making it handle a small fraction of the air volume and reducing the size of the valving in the link. While having only pilot flow will reduce the valve size, the overall "link" size may not be smaller so it can handle the mechanical stresses.
Sure, there is a very limited market here, but this is not only an A3 part, but could readily go on any deuce (and not be a $4,700 kit) by replacing the drag link and adding the cylinder.