I replaced the seats on an older, (late 80's) Overnighter with the exact model that BobP has indicated. They are just as he described... comfortable and sturdy. There really was a big difference in side to side support too. Very nice seat.
I'm sure the clearence in between the seats was reduced a little, (due to their larger width) but I don't recall that being an issue. I do remember it was very close on the other side of each seat, but they didn't rub. However, if I wanted the seats to face aft, I had to adjust the slider all the way back to rotate them without hiiting. Again... that was on a late 80's.