This is very cool. I'm afraid the only way to get a more accurate answer about the inlet/outlet ports airflow is nothing short of CFD. This is because apart from the inlet geometry, the current geometry of the cylinder and the position of the valve also play a role. A jet that enters the cylinder at an angle is more likely to "fill" it faster and "see" less resistance in the inlet part, due to a vortex created within the cylinder.
The model can be evaluated in e.g. 10 different positions of valve overlap for a given geometry, and the missing points interpolated.
Very impressive development of a configurable simulator using high frequency physical modelling.