With the closed chamber edelbrocks the .030 over 440 in my challenger is 10.2:1, .040 quench. It runs fine on our 91 octane calif pump swill, but does at times suffer from run-on. I've heard that was a problem with six-pack setups back in the day, and I have the idle solenoid on there, but hasn't helped much.
If I mix a couple of gallons of 110 in there, the run-on goes away.

I used to HAVE to mix in 110 at a 1:5 or 6 ratio when it had the iron 902's on it. It was only 9.8:1 then, but with the open-chamber iron heads, it pinged badly on straight 91.