That is a very specialized market. I'd be very leary about any of them that are available, and think you'll have great difficulting finding one that not only fits, but works well. I have no specific knowledge about those two. If at all possible, choose a 'normal' toilet, whether dual-flush or not, and put in a 12" rough-in, I think in the long run, you'll be much happier. The choises are much greater and the convenience if you decide it doesn't work to change it to one that does work won't hit your wallet anywhere near the same.