The OP asked
"for an iron headed small block at about 9.5:1 compression.
..what is the least amount of duration you can get away with
before you have detonation issues."
It's iron headed, 9.6 cr and I have no detonation at 91 or 92 octane...89 yes
And the smooth idle? He mentioned that in two posts, and alluded to it in at least a third. You mentioned the lack of smooth idle;to your credit. So perhaps totally useless was a bit harsh.
The recap is in post #27
