Dealing with dieseling-run on

[Kern Dog]

I got advised by some guy on another forum...he suggested that I try running race fuel.
Fuck that.....$15 a gallon gas to fix this? He also suggested backing off the timing or putting in thicker head gaskets to drop the compression ratio. When I politely declined, he got pissy.
It was shit advice but I was polite in how I disagreed with it.
First, this engine does not knock, at all. I dealt with detonation before with this very engine so I know what it sounds like, what it feels like. In 2022 I went through this engine and put in quench/dish pistons. This put the ratio to 9.8 to 1 and with that, it hasn't knocked once, even in hot weather.
I used to run 91 octane gas but tried 89 octane about 18 months ago and it ran great on that too, still no knocking.
If an engine isn't knocking, using higher octane fuel is a waste of money and possibly even reducing power since higher octane fuel does not burn as easily.
I'm not going to use expensive race gas to stop "run-on" in a street car. I'm not stupid enough to pull the heads to lower compression in a car that isn't knocking. I'm not backing off the timing for an engine that isn't knocking either.