You can't easily use the 1G stuff on the 2G. Not saying it can't be done, but AFAIK, no one has, so if you go this route, you'll be breaking new ground.
The upper triple clamp on the 2G B12N is different than the S model, it also has a different shell and facia for the gauges. The S models chrome shell doesn't go all the way around the gauges like the N does. For the cleanest change-over with OEM looks, you'd need those three pieces from a 2G N model.