B&M flex plate

Now that that is all cleared up, I hope Byron doesn’t mind if I swerve his thread a bit.
Can someone explain WHY they made the 360s external balance? If all 318/5.2 were internal balance, why the need to inventory different harmonic dampers, flywheels, torque converters and/or flexplates? It would seem only having 2 different cranks would make for less chance of mistake as well. Wouldn’t an internally balanced engine be smoother running overall as well?
It all come down to Cost. It’s cheaper to build a cast set up than a forged set up. The bean counters ruled the roost. Kim