The way you would normally kill an engine in flight is to shut off fuel with the mixture control.Note feathered prop planes like the 38 are different. The spark plugs are still firing. The same amount of air is going thew the engine, only no fuel mixed in. The prop continues to turn the same speed. The oil continues to pump threw the engine. When fuel is returned power return is instantaneous.
Note , the above description assumes constant speed props, not fixed pitch.
With the 38 for spin recovery, I would think engine select, followed by throttle cut would create more of a thrust differential do to prop drag on the idle engine to assist the spin recover.
P.S. I have had a real life fuel starved engine twice. Once while inverted, once when loosing a mechanical fuel pump.
HiTech