The new FLAT-6 RS motor is not only 12% more RPM, it also has 20% more torque, so you could gear it higher, and maybe improve theoretical top speed say 30% and still have acceptable braking for the higher speeds.
It has similar wattage ratings to the other motors mentioned above. Certainly worth testing as a drop-in....
I expect to have some in about a week, and will dyno a couple for my own curiosity.
Experience indicates they will probably exceed specification. I imagine Robert L. will have them on his test-bed as soon as they hit USA as well.
I will need one particular club track with a 10 metre straight so I can test them in a Nissan RAW for starters.
What sort of tyre compound and setup do you run for those speeds?