I've safely used a fel-pro 1059 at 12.5:1. main thing is keeping the fire ring away from the cylinder bore.
Thanks L is there a rule of thumb for how far away ?
i had to get my fel-pro catalog out to check the number. the number is 1039 not 1059, my mistake. this gasket was an easy/ reliable choice for a big bore and alum heads. rule of thumb on distance of fire ring from bore? I never came up with one but I know from experience the 1009 is a no-no. the 1039 has a 4.590" bore, per the catalog and the fire ring is comfortably distanced from the bore on a 400 or 440 block. I used the 1039 on a 4.375 bore 470.