Anything listed for the same year 650R will fit your bike, with the only exception being the internal engine parts(It's sleeved to make a 400cc engine).
The 400 was only introduced to certain markets to address licensing restrictions for new riders. Here in Australia, we got a de-tuned 650R for the learner crowd. If you knew what you were doing, you could have a full powered 650R in minimal time, while on paper you were still "legal".
One word of warning, Integrated taillights can be very hard to see during the daytime. The blinkers/indicators can be lost when braking. I had one fitted to my 250R, and regretted it.
Perhaps you could look at a fender eliminator, and some smaller blinkers to clean it up a little. Keep in mind also, you will need to upgrade your flasher relay if you go LED blinkers.