It's nothing too advanced. The Starblade gun controller is nothing more than a simple analog joystick, except with its directions reversed and two mounted grips with buttons. All you need to learn is the pinout for the PC game-port. Where the x and y analog inputs go and what potentiometer values to use for them. Usually for PC it is 100K pots, but any pot will do. I've converted arcade controlls on a few occasions using original SEGA pots of 5k each. Works every time on any PC.
Actually, the best and easiest for you would be to just buy a ready analog joystick, preferably USB, and gut it. Use the PCB and wire it to your cannon/yoke 's pots. Then calibrate it and you can play.