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

After actually doing some recalling in this thread I believe he was recommended to probably sell those and get the right Pistons I mean the creativity in the workarounds are pretty doggone redneck re-engineering science and I dig it, but man if you can get the stuff to work together the first time...
I can live with a head shim and open chamber 308 heads if the measurements are gonna get me a too thin crown/ dome. I will triple check everything.