In passing, all the bells and whistles on a modern ICE are there because of government mandates, or to allow performance during the various duty cycles demanded of an automobile power package. Each of them, automatic transmission, a/c, power steering, power brakes, emissions mandates, suck power and efficiency.
“Now, tune it to run precisely at 1750 rpm, direct couple the package to a 1750 rpm generator, and fly a drone with it.”
Why not direct to the propeller?