Max compression for pump gas iron head

What is the maximum compression ratio that can be run with good 93 octane pump gas in an iron headed motor. I am building a 318 with 302 casting heads and want to get the highest compression ratio possible without getting too close to the ragged edge of detonation on good pump gas. The machine shop will be decking the block to get my ratio just where I want it with the 59cc heads so I could really use your advise. thx
Author: admin