The double-decker Westland Wessex has a pair of side-by-side Gnome turbines low and forward (blue rectangle above).
What are the pros and cons compared to the center-high more typical placement of nowadays?
Of the cons is perhaps the longer shafts I drew above, which are concluded based on pictures that reveal the orientation of the engines and pictures of a partition between (but aft of) the two cockpit seats.
I searched for clear cutaways on Google and Flight's archive. Also checked the Wikipedia page regarding the engine placement.
The Wessex is developed from the Sikorsky H-34 that had a radial engine in the same location.