I'm with RustyRatRod on not jumping to conclusions without more details. Without the dynamic CR, how can anyone answer the question with certainty? One crucial factor that I haven't seen mentioned, unless I missed something reading through the thread, is the OP's elevation, which impacts cranking compression and therefore dynamic CR.
I take it that people claiming that 11.8:1, iron heads, on 91 octane is impossible have never bummed around the pits at Bandimere Speedway. Here in Denver at 5,600', the elevation robs us of approx. 15% cranking compression versus sea level, and that's with a less aggressive cam. Add more cam overlap and the dynamic CR gets skewed further. 11.8:1 here would have a dynamic compression ratio that acts more like 10:1 at sea level, which is certainly doable on 91 octane. I beat on a 383 with 11:1 compression, iron heads, 91 octane. No issues. I wouldn't have any hesitation trying for 11.8:1 if someone wants to buy me the pistons, cam, and converter:D At sea level, heck no, but not everyone lives at sea level.
