383 cast or forged crank

Ok Here I Go Again, I Got A Call From The Place Ballencing My Engine
They Said The Need The Flywheel/torque Converter Flex Plate And Damper Because It Was A Cast Crank External Ballance System.
When I Got The Motor I Was Told It Was A Forged Crank The Did Not Make A Cast Crank. I Want To Use A Fluid Damper And A 2000-2500
Stall Converter, Any Suggestios, Advice.

Thanks