Indeed other numbers are far more important, but here I was interested to see how much volume is displaced through these relative long and narrow tubes. Given your RPM range it does not look like the engine is struggeling to get the air in and the exhaust gasses out.
Laws of physic do not change, but scaling an engine down will change some important physical properties.
For example:
When scaling an engine by a factor of 2, the swept volume will reduce by a factor of 8, while the surface of the cylinder wall will reduce by a factor of 4. When building a true i.e. compression ignition Diesel engine, ratio between the amount of generated heat (compressed volume) over heat loss (cylinder + head surface) will become less favourable.
Basically why a mouse is the smallest warm blooded animal and the elephant, the former has the risk of becoming hypothermic (too cold) while the latter has the risk of becoming hyperthermic (too warm).
Furthermore, the swept volume (factor 8) will go through a valve surface (factor 4), reducing the speed of the air by a factor of 2. This can have the effect of bringing the flow of air from turbulent to laminar, which has dramatic consequences for the mixing of air and fuel in the cylinder.