To my knowledge each CID Amc motor has its own fly wheel weight measurement.
As in 232's take a certain weight,
258's their own
304 their own
My donor motor was a auto, with a flex plate, I'm reusing my standard shift t-18, so I need a Amc 360 flywheel.
Problem is all of the Amc's share the same fly wheel bolt pattern. Although they are not directly interchangeable..
Buying a fly wheel for your motor is a gamble. Mine came with my engine it was brand new in the box and the seller told me 3 times it's the correct weight.... I just wasn't sure.
I took the flex plate and the new fly wheel in to verify balance, and sure enough it was I correct.
They rebalanced it for me, to the exact same as the flex plate. 56.87 grams was the counter weighted balance for my Amc 360
They just drilled holes until it was correct.