If both are exacly the same timed and have the same wide exhaust port (the wideness is also a kind of timing) then I would expect an reasonable equal perfomance. You are talking about intake and exhaust timings, also crank timings, and crank bore?
The only other differences with Novarossi could also be made by the used materials. I know Novarossi has many piston materials to choose from and due the small expansion differences and friction factors that can have an effect on the overall performance.