Apart from the fact (already expressed by others) that the crust is usually considered a thin layer (40-50 km) compared with the rest of the planet, the issue is that such a configuration would not be natural.
If it was present at the moment of the planet formation, the layer of heavy alloys would have been melted, fused with other elements and most of it would be in the inner layers of the planet. If it was naturally added later, it would come from a massive meteorite impact with such a power that, again, would have melted most of the planet and buried most of the material, with the leftovers distributed all over the planet.
So, this design shows an artificial origin, and can be as un-spherical as the materials allow it. Which would not be that much, IMHO.
First, think only of the "half a crust" with the metal alloy part. A metal may seem to be very hard to bend, but when you put in under the pressure of kilometers and kilometers of the same heavy material, it will begin bending like soft wax.
The thicker/more desigual your crust is, the more plastic the base of the crust will be, invading the other part of the planet and making the metal crust thinner and thinner, until the metal has spread enough. To put an example, Earth mantle is highly viscous, but its composition is not that different from "rock-solid" Earth crust (if anything, it has more metal in it).
Additionally, the weight of all of that metal would depress the mantle itself (that, if it is Earth-like, it is not solid), sinking your metal layer deeper.
So, your metal crust will not be very tall (I bet something like 20-22 km tops). If you take into account that Earth radius is 6700 km, it would not make your planet distinctly un-spherical.
More thoughts about this, by someone who has done actual research