Bad vibes.

Assuming the cam was simply timed with the sprockets put dot-to-dot, was the crank sprocket keyway at about 1:30 looking at the front of the engine when the sprockets were do-to-dot? Just checking the damper position. The cutout ought to be almost centered on the keyway for that type of damper; a weighted damper would have it opposite to the keyway.

Any possible way that the flexplate is indexed wrong on the crank? When #1 is at TDC, the weight on the TC or flexplate ought to be at about 4 o'clock looking from the back of the engine. The 'bite' out of the B&M plate ought to be at about 10 o'clock.

And yes, all 360 cranks should be balanced the same.

Any cranking compression measurements that you can share?

Do you know the history of this engine? I've seen nothing posted that says for sure 'yes'....There seem to be number of assumptions being made, and some things not answered clearly.... since the most obvious things have not worked, it is time to back up and re-examine every small thing.