Hello All, I would appreciate your opinions, thoughts and experiences with rebuilding a late 1960s 440 for use with today's gasoline. I plan to go with the necessary modifications to accommodate unleaded gasoline. But what about the compression ratio? Will the currently available 91 octane "premium" grade work in a '68 or '69 440 rebuilt to stock specifications? Or should I have my machinist take the steps required to drop the compression ratio to 9:1? I know about the tricks such as retarding the timing or using a water injection system. But I also know that some older engines can be modified with different distributor advance curves and/or cam shafts with different lift and duration specs to allow older engines to retain their original performance characteristics with a lower compression ratio. Thanks in advance for any replies. Ken Josephson '68 Crown Four Door Hardtop