Your main issue may be width. If you can find the width of the galant ie. front wheel stance width and compare to U12. within about 100mm you should be able to make it work without cutting.
Other issue is the little lip down the side of the quarter panel infront of the front wheel arch/ under the turning light. U12 doesnt have the lip there so you might find a small gap opens up near the guard flare. Does look like a pretty good style match though.