Keith Black/icon advertised comp ratios

[rapidride3]

I believe Keith Black/Icon is closed on Saturdays. I am interested in the Icon forged ic 758 dished piston for a .030 400 chevy.

Their advertised compression ratio is 9:4:1

My question is,,, does this advertised compression ratio take into account the head gasket thickness????
I would like to lower by .2-.3 points so i can run 87 octane in my daily driver 76' pickup. Thanks, Matt.

 

[D&A Machine Shop]

Try their online calculator
http://www.kb-silvolite.com/calc.php?action=comp