Why turn the bowl? Can you just empty it? Valve on the "drain"?
Turning may help get rid of debris in the bowl, so that option is fine.
I would envision a low voltage 24 VAC synchronous motor (Hurst motors). 24 VAC for safety. These motors usually require a capacitor that's supplied. See:
https://www.hurst-motors.com/permanentmagnetacsynchronous.html the surplus market may work for you.
What you basically need is a disk with a depression along the edge in the up-right position where a roller micro switch resides.
The roller micro is designed to run the motor when it's not in the circular notch. The synchronous motor will generally stop instantly unlike other motors.
Thought needs to go into powering stuff. Low voltage for safety for the limit switch makes sense.
To make the bowl dump, you just have to short out the micro with a timer for a short amount of time.
If you can live with more than a minute to turn the bowl the project gets simpler, I think. Because timers with minute resolutions may be more common.
I doubt you need much torque, but that can be measured with a cantilever and weight or a spring scale and cantilever.
"smart relays" (Basically mini Programmable logic controllers)
here **broken link removed** is just one brand of a low cost controller. It can do the time, rotate and fill for you.