But he, and
people like him, say there's some secret boogeyman (usually it's
torsional resonance) just waiting to kill anyone who dares defy
Lycoming by not bowing down at their temple and paying up.

I have heard this very line before, unfortunately there is quite a bit of truth
to the boogeyman - LOL. Ask the guys that have been there and done that, and
have paid dearly (financially) in the process. They learned the hard way. Jim
Rahm come to mind very quickly. He poured everything into fighting the
"boogeyman".

I am certainly not saying, don't experiment. Experimentation is the path to
progress. But don't pretend problems don't exist, because they do. And
certainly don't believe that flying with off the shelf stock parts (i.e. Chevy
and Ford V8s) is safe, because it isn't. And last but not least, don't believe
that boat engine operations and aircraft engine operations are the same,
because they aren't, the dynamics are far, far apart.

With all the above being said, I wish you all the luck in the world with the
automotive stuff. But just don't blindly walk down the path, because the path
can end very abruptly.