I'm looking at going the other way 2012 engine in a 13+ frame. The early engines are a lot better to get power out of. And the 13frame has a different rake angle far better for track riding.
Well if a 2015 engine can go in early frame why not the other way around. I was speaking to ukrs and he says the best thing about the 13+ bikes is the rake angle. Faster turning.
It's already been done, Triumph left the engine mounts in the same place so it slides right in, someone was racing that setup on the roads this year. The old engine is far better for reliability once tuned as well, definitely the perfect combo.
I would really like to have further information from the project. What electronic package has been used? Any further info would be very happy to have!