I would be every surprised if we did ever see something like this. They would stick to the mainstream twine.
However if it was just a motor change I would be in for a triple Speedmaster after all it is all about being different. Since I have been riding the Speedmaster I have never seen another on the road. I have come across a few America’s. You know how great it is to go to a rally and know you have one of a kind there.