5.9, max safe compression?

Sometimes things just work out, like my friends 68 Roadrunner with a 400 based 451, reverse dome KBs for tight quench running bowl ported #452 iron heads, 10.5/1 compression. The dyno operator was amazed it doesn't detonate on pump swill, which is 93 here in Minnesota. The cam is 268@ .050( NOT a typo) .580 lift hydraulic, and hauls that full weight RR to 11.40s corked up. I would love to duplicate the same end result, IE, great results running hi compression and tight quench.
I read online an article (Mopar Muscle? HotRod?) put out yesterday saying Brian at IMM is working on a similar build, with very high compression, iron heads, and pumpgas. The article said 91 california swill will be the fuel. I Hope the writer got the facts right.