All machines are numbered the same way.
Airplanes, truck,cars,etc.,.
The numbering is always as if you are standing in back of the machine looking forward.
So on an airplane the engine, (when viewed from the rear) looking forward .
The left engine is #1 and so on just like your CB750.
Left cylinder #1
V-twin 4 cylinder (VF1000R) left front cylinder #1