converter?
I have had just 2 1972 340.
One was an auto it had electronic ign. And a cast crank. The damper Clearly said 340 cast crank only on damper.
You never said if you ran it like it is.
If you put the wrong damper andflex plate combo you would know It Right Away.
Other was a late 1972 but was from a manual trans car. It was steel crank as was most if not all 340-4 1972 manual tans cars.
So had neutral balanced damper and flywheel.