Head gasket recommendations for magnum

If the Piston is 49 in the hole, and you need at least 40 to the valve, you got no quench and be prone to ping. If you have the time and resources, I would be getting a valve pocket cutter and making room for those valves. You will need to find out just exactly how much room do you need and see if those pistons can take that deep of a cut. Otherwise I'd be looking at different pistons. In an ideal world you would have zero deck, ample valve relief, and 40 thousandths head gasket.