[Jibri Wright]

A 12.75:1 should be plenty. We were going to use a leads crew system initially as well, and the 12.75:1 gearbox worked like a charm. To tell you the truth, a Bane Bots 775 motor with a 64:1 gearbox is strong enough if you have two lead screw systems working in tandem.
The reason we switched is because the highest recommended speed for a lead screw bearing 60 pounds was way too slow. At the recommend angular velocity recommended by the manufacturer, it would take 20 seconds to move a hook 15 inches! So we switched to pneumatics for a faster climb.