1)Per the spec sheet on the Shure 562 dynamic mic- the sensitivity level is noted at -64dBV/Pa - this is at 94 dB SPL - What is the sensitivity level at 74 dB SPL ?
2) Is there a formula to get from 74 dB SPL to 94 dB SPL or visa versa ?
Simply subtract 20 dB from the sensitivity level to change from 94 dB input to 74 dB input. It's that simple. For your example of -64 dBV at 94 dB SPL, at 74 dB SPL the sensitivity is -84 dBV.
See the following link for more information:
How do I compare the sensitivity of two microphones?