compression ratio on pump gas

built a .060" 360 awhile back, ran the KB190 quench dome pistons with 915 heads, compression was around 10.3, cam was the XE284H, Alt was 3700ft, ran great on premuim, I now have a 406 sbc with 10.4x compression & iron eagles, Alt. is 1600ft., small cam & it runs great on 91 octane.