Do any horizontal engines count here or do the cylinders have to be on
opposite sides of the crank?
  In the 50's John Deere tractors had two large horizontal cylinders
side by side with the top of both pistons facing forward.  To start them
you hand cranked an exposed flywheel on the side of the tractor.  To get
a fighting chance you opened compression release valves on both
cylinders.  When I was a teenager I was just heavy enough to turn the
flywheel by hanging on it and could sometimes start our John Deere.
Since there was no provision for retarding the spark while starting, it
sometimes kicked back...great fun.

Larry A.
Chicago
ex farm boy