5.9, max safe compression?

gregsdart said
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.

In a way, your friend's 451 running that SCR is not particularly daunting. If your numbers are right, with that level of cam and running a guess-timated ICL of 106, he is roughly in the 7:1 dynamic CR range. His speed is from the cubes and cam; I bet that thing has to rev a fair amount (considering the stroke).
So you are trying to duplicate THAT result? Or make something that is an all around engine with gobs low end torque? The latter is where AJ and I are coming from but that may not really what you are looking to do.