Engines with he 819 head came from the factory with flat pistons. However aftermarket pistons with a dome were offered through the years to raise compression ratio. The factory domed pistons that came in an engine with a 477 or 412 head will not work with an 819 head. The dome will actually hit he head. The aftermarket domed pistons for the 819 head raised the compression ratio considerably. The higher compression ratios usually required the use of high octane gasoline.
https://photos.app.goo.gl/DMGyg4wXsoEz4ZGv5Above is a link to what a factory domed Zollner piston would have looked like that came in our engine from the factory. It would hit he head on a 477 or 417 engine. What you have is aftermarket high compression pistons. Running gasoline with too low octane may have contributed to your failure.
