Use a table ban saw to hack off the 340 piston crown .

Okay I looked up the KB 243, which is a flat top piston. You called it a crown and I was thinking dome in my first reply. There is no way you can cut .100" of the top of that piston even

lathe cut and expect it to live. I've cut really thick old forged TRW pistons off in the lathe and ended up with .110" top thickness when I was done. Those KB 243 pistons are

Hypereutectic and they aren't nearly as strong as forged pistons are. You're going to do as you like, but I am still doing to say it's a bad idea.

Good Luck,

Tom