I wonder whether there is a retired Chrysler employee
who saved a dyno room graph that plotted
the Octane rating of pump gasoline versus the Compression Ratio of a test engine,
hopefully the 1992 Magnum 5.2 V8?

Octane could be Research, or Motor, or EPA Anti Knock Index.

Compression Ratio could be either static, or the more predictive Dynamic.

I am not sure if Willem Weertman is alive or answering questions,
but he was the chief engineer
and he cared enough to write a book.

Since we are in the “Incredible Transition” to battery electric vehicles
you would think secrecy about such cylinder head knowledge would have lessened to near nothing.