This motor had no issue with detonation ,If it had the pistons would have been all pitted up and so would have been the valves Or even the head maybe. And I have Photos of the pistons.And Like i said I am still useing those same pistons in another motor.
I found this gem in "Engine Design", by a J.G. Giles in a 1968 automotive technology series book:"For a fuel of a given octane number the onset of detonation is influenced by the compression pressure and therefore compression ratio at fully open throttle, by the temperature of the incoming fuel/air charge, by the mixture strength, and by the characteristics of the combustion chamber. It is therefore not possible to say what octane number fuel may be used with a given compression ratio or the other way round, and the actual requirement of the engine in terms of octane number must be determined experimentally."
So the correct answer is: There is no correct answer regarding simple compression ratio vs octane rating. I like it!