I remember the megadrive pad runs fine without modifications (fire 2 included i think) on a1200 just some games uses more than 2 fire buttons.
The problem on an A1200 is that many games use "up" on the D-PAD to eg. jump or accelerate a car, making it very awkward. i just soldered a wire from one of the button pads to the up pad on the circuit board.
