For the rercord...I still have the orginal 11:1 stock pistons in my 70 Z with the Crane cam and it runs just fine on 93 octane pump gas. I do however add Max Lead to the gas which puts the lead back in the gas, and also raises the octane level to around 100 or 101. I found a place to buy Max Lead for 45 bucks a gallon and 1 gallon usually lasts me the entire cruisin season. Anyone interested in usuing Max Lead can read about it and buy it here:
http://www.maxlead2000.com/