6.123 H or I beams. I liked the Mahle pistons, but my machinist told me their only about 9 lbs on the ring pack, not enough for a modern ring set for a 10:5 street/strip engine. The Molnar crank is on order, with the correct bearings. The block is being line bored, and set up for ARP studs and a windage tray. My Lunati 733 cam kit should be here in 3 weeks. Okay, Gentlemen, how much compression can I get away with using 92 Octane cat whizz gas and this big solid roller cam? rumblefish, Yellow Rose, and all others willing to chime in? I'll be happy to provide more specifics as the build moves on. I appreciate all positive input for my 408.