Is the dark patch below the rings blow by or just the coating which hasn't worn off near the rings (where the piston rocks back and forwards less)? I had assumed the later, but on closer inspection you can see somewhere there was no coating. Ring end gap should tell the story.
Increasing comp will definitely reduce top end and over rev, however lifting the cylinder (more gaskets) to time the ports (exh to be full open at bdc) will get you a peakier power delivery. Having the head worked after this should correct the squish, put the CR wherever you want it, and also improve efficiency across the board.
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