Mr T..........take yer sleeves OUT and run bigger pistons. By definition, you have increased yer compression ration. (ratio of swept volume to combustion chamber volume)
As the flathead V-8 guys have found out, It is really difficult to increase compression. Since ALL cylinder heads are interchangeable, Buy a NEW 8N cylinder head and gitt 6.5:1 compression.
Howsomevers: you want more power? Gitta 454 Chevy smog pump and NAA carb and SUPERCHARGED yer engine. You doubt? Google "Dirt cheap supercharger by Steven Richmond" ........Dell