Yeah, well i'm in full learning mode here. How many bolts in a standard 426 Hemi head? As far as the bore goes, the block is offered in a 4.240 and 4.590 bore. I haven't checked , but thought there would be a piston for the 4.590 bore and if not it would have to be custom. My thought was, why would BM sell a block with that bore size if there is no piston available for it, so didn't give it anymore thought. I'm sure it will fit, i just want to know in advance so i can prep the engine bay before i get it on a hook.