compression ratio vs octane

idrift,
I didnt think I would see this post again. I cant tell you if your pressure reading is the same as cranking pressure, but I think it is. If so 190psi is still in the range for 92 octane, but at the very top of that range.

I would not put in a knock sensor if you have valve train clatter it would be useless.

If this issue is really critical you need to pull a head and go through all of the measurement steps to calculate your engine's specs. this will also give you the ability to inspect the cylinders for signs of improper ignition.
hope this helps,
Andrew