Assembly and fielding help

Hey team! I have a Spearhead and some Gossamids I’m getting ready to assemble, and I just wanted to ask about how aesthetics may affect gameplay of tournament viability.

I do want to build a Durthu instead of a Treelord for my first big tree, but the head and skulls aren’t my favorite look, I love Sylvaneth for the look of leaves and mushrooms and pure nature vibes. Would I be okay to use the Treelord’s head and shoulders on the Durthu body legally? Magnetization also isn’t out of the question if that works well enough on this model. For context, I do plan on picking up a second Spearhead at some point, so I’m considering just building both models as intended in spite of the skulls.

And on that note, are Kurnoth worth magnetizing or are their limbs a bit fiddly?

Thanks in advance!