Help Gathering Info on Inherited Motor

Compression ratio is NOT the engines enemy.

Uncontrolled combustion in the chamber is, and is usually called detonation, but may be preceded by pre-ignition. These are just fancy words that mean the fire starts before you told it too, like a rebellious child testing your patience.
Your tools against detonation are;
1) lower cylinder pressure. NOT lower compression ratio, they are NOT the same thing
2) increased anti-detonation resistance in the fuel.
3) less heat in the chamber; which could be;
--A) retarded timing
--B) removal of hotspots in the chamber
--C) coolant injection

Which one or combination you use depends on what the engine is detonating in response to.

As to just driving it now and then, the only limiting factors are
1) detonation
2) aka; pinging,
3) aka; can of marbles,
4) aka the rattle of death.
You can control that with your right foot. When you hear it, you simply lift off the gas a bit until it goes away.
Obviously;
you start your morning with fresh hi-test, and
you feed that engine fresh cold air; DO NOT try to force-feed it the HOT underhood air. Then
keep the running temp to 185 or less, at least during your getting acquainted runs. And
then just be conservative on the timing until you get to know all her normal noises. Sneak up on it.
and Disconnect the Vcan for the first few hundred miles.
Tuning might be a beotch tho,lol.