All in all, I think the airplane was an Edsel for Cessna and a misadventure
to say the least

I don't know why you are saying this. How many Edsels were build and
sold by Ford? Compare that with the many hundreds of Skymasters that
were build and sold.

I do remember someone tacking on a
turbo on the 337 that attracted a few buyers, not nothing to write home
about.

There are hundres of Skymasters with Turbos both pressurized and
non-pressurized (P337).

Gerd (ex Skymaster owner)