Which makes sense. They are supposedly lighter at the small end only.
But I don't think the crank needs to be rebalanced..... the change in the extranal weights makes up for the bobweight change fo LA vs Magnum. I suspect it will not be balanced within 1 or 2 grams this way, but will be balanced to factory levels. 90% of the balance work change on these cranks takes place at the 2 large counterweights at each end anyway, which is where the external weights add in.