If you look up Dave666's long story of making a splitter and diffuser for his Gen 2, you will see I posted pictures of my version of the Gen 1 Roe chin duct. It was surprising how different it is underneath. I recall the holes for the Roe duct were behind the teeny chin spoiler hanging down from the fascia on the Gen 1, while the Gen 2 holes are ahead; meaning the position of the chin spoiler strip moved.
So it may still fit, but ...