Looks like compression would be about 9.8:1, and they would sit 0.045 below deck height. Those pistons hold a lot of power in K20's.
The pistons sitting low in the bore might cause additional stress to the top of the cylinder on combustion. I definitely have never seen an oem engine with a piston that recessed. You could deck the block .045 and have 10.8:1 compression which is fine for e85 and boost. However at that point I'd be concerned about P2V clearance. The valve spacing and angle is probably different between the two engines. Even so it could be made to work with some clearancing, as long as it doesn't need too too much. (this would involve removing material from the piston.)
The only way to know for sure would be to assemble the bottom end (Well just one piston/rod combo really). Then put the head on and clay the motor.
It's definitely not something that could just be slapped together as it would involve machine work on multiple parts.
Even if it works it's a lot of work for not a lot of benefit. Unless you have the parts and are experienced building engines and modifying parts, just turbo a stock H22 and save for the Mahle gold pistons and forged rods.
