Quote:

Forged crank was new for 440 in 73, 71 for 383.



Don't you mean Cast?

!970 should be forged but as stated above it certainly could have been changed in the last 41 years.

Even if you do have the original forged crank you still need to determine if it is internally or externally ballanced so that you can install the correct damper and flywheel or converter.

In theory, there is no difference between theory and practice. In practice, there is.