I have built and run 10:1 engines on 87 octane with iron heads and very mild cams on several different makes and sizes, so I know how to do it - but not everyone does. I started doing this over twenty years ago. I've always been after power with good fuel economy, and overall engine efficiency is the path I've chosen to achieve both goals.

I also regretted running too much compression in a couple of street engines because it cost more in higher octane fuel than the extra power was worth. I still will build to the edge but only run 87 octane in my drivers. The extra cost in Canada is at least $.10 per litre for mid-grade and $.20 for premium. That comes out to $.33 and $.66 per gallon in US measure and money.

Until all the engine builders are willing to do more than a quick rebuild, the best advice is to keep the compression down or find someone who will build it right.

No wives' tales involved, just common sense.

Tom, I suspect that the .023" down the bore was to allow the proper piston to head clearance (around .040") with the steel shim head gaskets. I know that is definitely the way the engineers designed the OHC engines. When using the thicker Fel-pro gaskets, zero-decking will bring the clearance back to factory specs and compression.