Yeah, doesn't matter what your pistons are made of, a bad tune under load will destroy them in a heartbeat.
7 mains make the bottom end pretty tough. The bottom end of my OHC is essentially the same, just a deep skirted block (originally designed with cross bolted mains in mind but never happened). My plans are like yours. Forged pistons, cleaned up and checked out stock rods with arp bolts, then boost the piss out of it until I get nervous, can't keep a head gasket in it, or can't keep detonation at bay. If I can keep the tune safe on all cylinders, I'm hoping to see where the next failure point is, rather that is detonation, crank or mains.
