Putting a hose fitting on adaptor for flushing !!!

After sitting and looking at a 56 ci omc adaptor and thinking about flushing the motor without it running, I have an idea of putting a brass fitting into the
side of the adaptor on the water intake side.
I know this would only flush the engine block and not the water pump etc (although a slight bit might go down there too) it would be good for when not
realy wanting to start up the engine.
The fitting could be a one way valve or with thread and cap that can be taken off for when flushing, either way this could be used to just simply fit a hose
and just flush the engine without needing to run it.

maybe some of you already have a similar thing on your motors ?

Is there any reason this should NOT be done ?