One thing that has not been mentioned is that the inverted V also gives greater propeller clearence...something that you don't have to worry about! Leave the engine right side up and save yourself a multitude of problems! These engines were not designed to be turned upside down. You would be risking hydrolic lock from
oil seeping in to the combustion chamber past the rings when it is at rest for an extended time. Just like having to pull a radial engine through by hand before you start it when it is cold, I would think you would need to "pull the engine through" a couple of cycles to make sure that
oil has not collected in the cylinders, like you would an airplane, before you hit the starter! I have seen radials that have "locked up" in in less than two turns because of
oil in the lower cylinders! It gets REAL EXPENSIVE REAL FAST! I know, as I have flown many old airplanes and currently fly a 1937 Howard DGA-11 with a Pratt & Whitmey R-985.
And yes, you would have to scavange the oil from the crankcase just like an aircraft engine! Just my $02!
Good luck!
Mike