Your post infers that the unique nature of the M110 requires a fuel shutoff for any carb fitted to it. What is so unique about the M110 that would require fuel shutoffs? The vast majority of pre emission motors fitted with carbs did not have fuel shutoffs and operated just fine.

Fuel shutoff solenoids emerged as a response to emission control devices such as lean jetting, air injection, EGR valves, and ATDC timing. None of which my M110 has.

I doubt the M110 has a design that is so unique it requires a fuel shutoff to function correctly. I asked my original question because I suspect that maybe something else is going on, like cam timing being off, which might explain it. Or maybe an explanation as to what the cough actually is.

Whatever it is it is related to the speed of the engine at shutoff. If the car is in (D) 900 RPM, then the idle is lower at shutoff and I don't get the cough. It's only when the car is in (N) 1200 RPM at shutoff do I get the cough.

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1974 280C MBZ
1995 BMW 840 Ci
1999 996 Cabriolet Porsche
2005 Toyota 4Runner
1974 VW Westfalia camper P27