turbo or NA?
power expectations?
the head strength isnt really an issue here... they are all "strong" and cope well with NA or forced induction duties... the blocks however differ with the 20V blocks being towards the lighter rotating bottom ends for higher revs yet more then enough strength for stockish duties... wwhere as the 4agze has forged pistons and rods and will handle boost from either SC or turbo.
so its all relevant... no point in going the GZE bottom end cause its the strongest if your planning on staying NA