Engine configuration

"Certain types of V engine have been built as inverted engines,
most commonly for aircraft. Advantages include better visibility
in a single-engined airplane, and lower centre of gravity."

An aluminum V8 was adapted in the 1960s to power ---I want to say the
Whittman Tailwind, but I could be wrong --- it was run direct drive and
inverted. Ran fine for many years. One problem was that the oiling system
had to be redesigned. It was originally designed to pump oil up into the
valve covers, then let it drain back down. Obviously that won't work if the
whole engine is upside down. Also the carb had to be replaced (float bowls
don't work upside down either.) Neither change is trivial, both are do-able.

You can see why it would result in a lower center of gravity - the crank
(directly connected to the prop) becomes the highest point on the engine
instead of the lowest. Same for visibility - the whole engine is lower and
out of the way.

But that all assumes you are going to use it direct drive - which almost
nobody does. If you use a gearbox, belt PSRU, or HiVo chain PSRU, they will
all give you an offset of several inches, making for the same center of
gravity without the other changes, and allowing for much greater power,
because engine RPM's can be run much higher for the same prop RPM.