Believe it or not
Balancing machines, which measure imbalance moment (not torque, albeit with the same type units) are commonly calibrated in gram-inches. Why these bastard units, I have no idea.
Inches per second is indeed a velocity, in this case the velocity amplitude of a sinusoidal vibration waveform. To convert to imbalance moment (see above) one would have to factor in the prop mass, balancing rpm, & maybe a few more unknowns that escape me at the moment.
But both are common imbalance / vibration measures.