LA vs. Magnum block

Why did they replace it with a magnum block? If you have all the components for the LA and that's what you wanted I would stand my ground and ask for the LA block. There are quite a few obstacles to overcome swapping to the magnum block and it all equals more cash out of your pocket. Especially if you already have the cam, heads, and block components. Don't forget about the valve covers too if you go with magnum heads.