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?

Yes Roelof the only difference being even only ports 9 against 7.
The progress of the engine will be very similar or even equal to the little I already understand.
Because of the price difference that still is some of a 9 port for a 7 port.

Thank you