Head gasket recommendations for magnum

Block has been decked and has .020 over flat top pistons, no valve reliefs, Cam is a .490/490 lift with 108 lob separation. I bought the short block part from a guy that was gonna build it up but he never got around to it, never said how much it was decked. Heads were rebuilt from a shop that i believe they surfaced the head, cant remember. Do remember It was somewhat of a rush build since i was wanting to drive my car to minnesota at the time and the cam supplier recommended this cam so put it together and ran great untill now.