Cast crank or steel crank
Hey Dorian, and yes the cast crank is externally balanced and needs the big wide vibration dampener
http://www.moparts.com/Tech/Archive/bb/22.html.
Your other option is to purchase a stock forged crank, they're not that expensive or you can probably get one locally in good shape and just have it polished up. As far as the flywheel goes I ain't got a clue but I've never heard of a non steel flywheel, doesn't mean tho that they aren't out there but call these guys, they'll know for sure.
http://www.hughesengines.com/
Terry