Fat lobe blanks? I have no rhyme or reason on who uses them or how to make sure your next cam either is fat or skinny, My HO. Racing HC-03 Lunati 30706 and Comp 296AH-8 Are fat blanks... Hand full of others I have are skinny..
Your current engine, the main bearings if when you pull the crank out and the bearings just kind of pop out of the saddle you still have a problem that points to detonation, I'm not convinced your old flex plate took out your old crankshaft I however would believe a harsh vibration as in detonation took out both of them the converter and healthy flex plate absorbed enough of the vibration to keep the crank alive but when the flex plate was unable to absorb any torsional vibrations due to advanced cracking then the crank failed ...
Hope you get it sorted out and have fun soon
