So if I found a low hour used engine I would need to make sure it was a V2203-M and I would be good?
Not really the whole story.
It can be a V2203M can be a IDI or DI engine.
The IDI and the DI have different Intakes and Rear end plate (bell housing and starter attach to that plate) mounting and a host of other details that could be different.
But depending on how the pump attaches to the back and depending how the air cleaner attaches a DI might work.
Also a V2203M-B, V2203MB, V2203M-3B, V2203M- GSB is a fixed RPM engine
I could go on and on with all the other variable possibilities there are, some things are easily externally changeable some are not.
It really all depends on the exact build of the motor.
Based on the description alone of your Ex, you are actually looking for V2203-M-E2BH-2-N/3-N
If you give me the units serial number I can be more exact on the exact model number it used.