hello...well you can raise compression by decking block---however, you will have to mill top of piston also....so 1st mill/deck top of block...when you do this piston will "stick out" top of block...so to remedy this ,you need to mill top of piston-this is done alot-.....and when this is done you make dish is piston less and this raises compression.....
did i explain this ok?

Lee

and by JUST cutting off top of piston DOES NOT raise compression, but combination of decking block AND cutting piston top DOES raise compression