[HawgRyder]

Some top rings need pressure to seal completely (or close to it).
Dykes type rings are like that.
Also...some pistons have small holes drilled from the top down into the back side of the top compression ring land for this reason.
If you take that into account...I think Andy is correct...the static compression might be within the limits for the octane used...but the running ratio goes higher...and you run the risk of knock or pre-ignition under those circumstances.
Bob