Perhaps a thick head shim would be a better way to go about creating a lower compression ratio.
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Resorting to crank and block combinations seems to be alot of effort for what you want to achieve. I had one made out of 3mm plate.

Of course the next major obstacle (following the countless many) would be blowing head gaskets and piston or conrod failure.

Once you sort those issues it'd be interesting to hear how it goes.