Goldfinger
You said it, "almost" is not the same:
NS is 13.80x14.00mm
RR is 13.70x 14.25mm
So RR has a longer stroke (.25mm longer) , which means that port timings must be different to enhance torque, etc. It is the first true long stroke Nova .12 engine, which isnot the same as the old Nova-Mugen MT12 which was a long conrod engine but with same stroke as the rest of Nova based engines.
AFM