Your diagram shows first, second and third harmonics. Tuning for harmonics is only for overlap period and for low rpm setups have about zero effect on anything. What matters for tuning is max cylinder vacuum to intake close point to achieve high pressure to intake closing point. It's more than just frequency as target is to achieve max VE not max pressure.
With IR-setups it's very easy to have different length velocity stacks to change tuning point, shorter stack means more power top end power, taller stack increases mid end power. Mild camshaft setups don't give a shit for harmonics, top end power is intake flow limited and shortening manifold will increase top end power. But tuning only for top end power is just stupid.....
And good IR intake length is usually as long as you can fit in. Intake from head to carb should be as straight as possible for even fuel distribution, velocity stacks could be bend to 90 or even 180 degree if needed.